Teaching Guide and References - Sci-Bono Discovery Centre

Engaging Electricity 

Exhibition Guide 

Copyright Sci-Bono Discovery Centre 2012 ME 21/11/12 V7 1

An Overview of Sci-Bono 

Introduction 

Sci-Bono is South Africa’s premier science centre. It supports maths, science and 

technology (MST) education and offers innovative, dynamic learning experiences that 

contribute to building South Africa’s science, engineering and technology capacity. 

Located in the cultural heartland of Newtown, Johannesburg, the centre houses a 

collection of a few hundred interactive MST exhibits and exhibitions. 

Initiated by the Gauteng Department of Education (GDE) and the private sector in 2004, 

the centre is currently responsible for leading the Gauteng Mathematics, Science and 

Technology Strategy for the GDE, and receives annual funding for its mandated operations. 

Sci-Bono operations are governed by a long-term memorandum of agreement. 

Sci-Bono has strong relationships with industry stakeholders and international 

governments that provide both programmatic support and funding for specifi c projects. 

Sci-Bono has grown to become one of the most popular leisure and educational 

destinations in Gauteng and is open to schools and the public seven days a week. 

Vision and Goals 

Sci-Bono envisions a society with the capacity to compete in the global world of science 

and technology, a society equipped with the skills, attitudes and values needed to 

improve the quality of life of all South Africans. Sci-Bono works towards achieving 

this vision through the following goals: 

• Improving the teaching and learning of mathematics, science and technology 

in Gauteng schools 

• Providing career education to all learners in Gauteng 

• Promoting and improving public awareness of and engagement with science, 

engineering and technology 

To achieve these goals, Sci-Bono offers a wide range of annual programmes, 

workshops and exhibitions for learners, teachers and the general public, at its facilities 

in Newtown and through an extensive outreach programme in schools throughout Gauteng. 

2 Copyright Sci-Bono Discovery Centre 2011 2012 ME 21/11/12 V7

Table of Contents 

Page Numbers 

Exhibit info Teachers Guide 

ELECTRIC CIRCUITS 

1. Is it a Conductor 2 60 

2. Completing the Circuit 4 62 

3. Puzzle Circuit 6 64 

4. Electricity travels through my body 8 66 

5. Feeling Electricity 10 68 

6. Bright Lights 12 70 

7. Filament in a light bulb 14 72 

8. When Current Flows Things Heat Up 16 74 

9. Vehicle Indicators 18 76 

10. More Lights More Current 20 78 

11. Ohm’s Law Demonstrator 22 80 

12. More Batteries Please! 24 82 

13. Selecting the right battery 26 84 

14. Current Flows Battery 28 86 

15. A short journey into electricity 30 88 

16. Beware of a Short Circuit 32 90 

17. Electricity Safety 34 92 

ELECTROCHEMISTRY 

18. The Human Battery 36 94 

19. What is inside a battery 38 96 

20. Current Flows Electrolysed 40 98 

ELECTROMAGNETISM 

21. Jumping Disc 42 100 

22. Current flow magnetised 44 102 

23. The Motor Effect 46 104 

24. Electromagnetic Induction 48 106 

25. The Generator 50 118 

ELECTROSTATICS 

26. Electric Fleas 52 110 

PLASMA 

27. Luminglas 54 112 

28. Spark Plugs 56 114 

29. Jacob’s Ladder 58 116 

Copyright Version Copyright Sci-Bono Discovery Centre Centre 2012 2012 Copyright Sci-Bono Discovery ME 21/11/12 Centre ME V7 21/11/12 2012 V7 3

How to Use this Exhibition Guide 

This exhibition guide has been developed to enable you to find out more about the Sci-Bono 

Discovery Centre exhibitions. It will enable you to continue the wonderful journey of discovery 

at home or in your classroom. 

The document has been divided into two sections: an exhibit guide and a teaching guide. 

The Exhibit Guide explores the science concepts that relate to the exhibit, day-to-day applications, 

historical stories and activities that you can do on your own. The Teaching Guide provides teachers 

and parents with examples of how the exhibit links to the school curriculum and lists some 

[interesting resources related to the exhibit. 

Keep an eye out for the following sections in the Exhibit Guide: 

The Exhibit What is this exhibit and what can I do with it or to it? 

Intriguing Information What is so awesome about this exhibit? 

History Relevant and interesting historical information. 

The World at Work What are some real world applications of these concepts 

More to Consider Take an even deeper look at the concepts 

Try this Out! Some cool stuff you can do at home or at school 

Here is what you can expect in the Teaching Guide: 

Exhibit objectives What could you experience from this exhibit? 

School Curriculum Links So where does this fit in with my school work? 

Q & A Some questions you can ask your friends, children or students. 

Links to Websites and You want to find out more ...check these great links! 

References 

Figure references Where did we get these cool images from 

The map of Sci-Bono Discovery Centre is designed to help you find the various exhibits related to 

this guide. Remember, without exploration there is no discovery. 


Is it a Conductor? 

The Exhibit 

In these two exhibits, different types of materials are tested to determine if they 

conduct electricity. In “Is it a Conductor,” visitors are able to identify which materials 

are conductors by trying to complete the circuit using each of the materials present. 

If the material conducts electricity, then the current flow is indicated by an ammeter and the sound 

of a buzzer. In “The Current Only Flows through a Conductor,” different materials 

contained in tubes with metal ends are placed in the circuit. Materials that conduct electricity 

will be indicated by the illumination of a light bulb. 

Figure 1: Is it a Conductor exhibit Figure 2: The Current only flows through 

a Conductor Circuit exhibit 

Intriguing Information 

In the atoms of some materials, 

such as metals, the outermost electrons 

are loosely bound and are free to move. 

They are called free electrons. 

Materials that have high electron mobility – that 

is, many free electrons – are called conductors. 

Insulators, on the other hand, have electrons 

with low mobility. They have few or no free 

electrons. This is why they do not conduct 

electricity. 

Figure 3: Free Electrons 

History 

In the 1700s, Stephen Gray discovered conductivity. He found that electricity could 

be transmitted through another human body. 

In 1752, Benjamin Franklin reasoned that lightning is electrical in nature and that charges will 

be conducted along a metallic material. After his famous experiment flying kite into storm clouds, 

he invented lightning rods, which are placed on top of building in order to protect it from 

a lightning strike. When lightning strikes the rod, instead of passing through the building 

and causing damage, it is released into the ground by a connecting wire. 

Copper is a commonly used conductor due to its high degree of conductivity. 

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The World at Work 

The best conductor of electricity is silver but it is not commonly used due to 

high cost. Copper is the most common material used for electric wiring. 

Gold is used for high quality surface-to-surface contacts because it does not corrode. 

Not all conductors are metallic. Some examples of non-metallic conductors are graphite, 

salt solutions, and plasmas. 

Insulators do not allow for the flow of electricity and are used to protect us from the harmful 

effects of electricity. For example, the coating on electric wiring prevents electrocution. 

More to Consider 

Superconductors are objects that 

conduct electricity and have very 

little resistance. These objects can 

only be classified as superconductors 

below a certain temperature. 

They have found applications in 

such things as magnets in maglev 

trains and in biomagnetism in 

Magnetic Resonance Imaging (MRI) 

brain scans. 

Semiconductors are made from non-conductive materials such as silicon. 

Small amounts of impurities are added to the silicon to make it slightly conductive. 

By this method the type of conductivity it displays can be controlled. Semiconductors can be found 

in microprocessor chips and transistors. Anything that is computerized or that uses radio waves 

is dependent on semiconductors. 

Try this Out! 

Here’s what you’ll need: 

• 1 battery (1.5V) 

• 2 pieces of electrical wire 

• 1 standard flashlight bulb (1.5V) 

• A roll of cellophane tape 

• Small pieces of plastic, wood, glass, copper wire, silver ring/chain, 

gold ring/chain, rubber and paper. 

Figure 4: Copper Wiring 

Here is what you do 

1. Tape the end of one wire to the positive (+) end of the battery and a second wire 

to the negative (-) end of the battery. 

2. Touch the free end of the positive (+) wire to the metal side of the bulb right below the glass and 

the free end of the negative (-) wire to the little silver tip at the bottom of the bulb. 

The bulb should light up. Now you’re ready for the challenge! 

3. Hook up the small piece of plastic at the free end of the negative (-) wire to the little silver strip 

at the bottom of the bulb using the cellophane tape 

4. Repeat step 3 with the wood, glass, copper wire, silver ring/chain, gold ring/chain, 

rubber or paper. 

5. Write down whether the bulb lights up for each material. 

6. Draw two columns, one labelled conductor and the other insulator. 

Place each of these materials in the correct column. 


Completing the Circuit: 

The Exhibit 

These are the three exhibits that demonstrate 

the requirement of a closed circuit for current 

to flow. 

In “Completing the Circuit,” visitors connect the loose wires 

to complete the electrical circuit. The current flow is indicated 

through the illumination of the lamp and the sound of 

the buzzer. 

In “The current only flows when the circuit is closed,” visitors 

turn the handles of eight different switches in order to 

close the circuit. A closed circuit is indicated by the 

illumination of a lamp. 

In the “Which light bulb does not work?” exhibit, the filaments 

of six light bulbs are examined by visitors. The one with 

the broken filament does not light up. This implies a 

broken or incomplete circuit. 


The flow of electron in a closed circuit produces electromo 

tive force (EMF), which can be used to do work, such as 

light ing a light or heating a room. EMF refers to the external 

work expended to produce an electric potential difference 

across two open-circuited terminals. Electrons will only flow 

when there is a continuous path from the negative terminal 

to the positive terminal. The amount of electric current is 

measured in Amperes (amps) and the symbol used is “A”. 

The EMF is measured in volts. 

Electron 

Source 

Electron 

Source 

no flow! no flow! 

(break) 

Figure 4: Break in Circuit – No Flow 

(break) 

flow 

no flow! 

Figure 5: Continuous Circuit – Flow 

Electron 

Destination 

Electron 

Destination 

Figure 1: Completing the Circuit 

Figure 2: The current only flows when 

the circuit is closed 

Figure 3: Which light bulb does 

not work? 

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History 

William Gilbert first discribed electricity in the 16th century in England. In 1729, 

Stephen Gray discovered the principle of conductivity. By the end of the 1730s, 

positive and negative charges were discovered by Benjamin Franklin. Thereafter, 

the explorations into electricity were taken on by many scientists such as Musschenbroek, 

Allesandro Volta and others. 


In electronic equipment such as computers, radios and cell phones, 

electronic circuits are imprinted on circuit boards. These boards, 

also known as printed circuit boards (PC boards), have the circuit wires 

imprinted onto a thin piece of synthetic material. 

PC boards can be complicated circuits that connect thousands of resistors, 

capacitors, and transistors to create microprocessors that make 

computers possible. 


Try this Out! 

Every electric circuit has four basic parts: 

1. An energy source, such as a battery or power point. 

2. Electrical conductors. These are the wires that carry the 

electric current. 

3. Electrical load. These are devices that use energy, 

such as a light bulb, computer, or heater. 

4. Switches. They open and close the circuit and as a result, 

turn the electrical energy on and off. 

You will need one or two 1.5V (AA or AAA) torch batteries, a torch globe, 

and some thin insulated electric wire. Try to construct an electric circuit with 

these components so that the globe lights up. What can you do to the circuit if 

you need to open or close it? 

Caution: You should not attempt to work on domestic electrical wiring, switches, 

or electrical outlets unless you are properly trained and equipped to do so. 

Copyright Sci-Bono Discovery Centre 2012 Copyright Sci-Bono Discovery ME 21/11/12 Centre V7 2011 5

Puzzle Circuit 

The Exhibits 

This exhibit is an example of a parallel and 

series electric circuit that contains a cell 

supplying power to a branched circuit. The 

main circuit and the branches have ammeters 

which measures the amount of current. 

The branches are also equipped with lamps 

to indicate current flow. Visitors connect the 

loose wires of the circuit in order to close 

the circuit at different points 


A parallel circuit is used to deliver electricity to all appliances in a house, including outlets, 

lights, dryers, and refrigerators. The electrical current is divided in a parallel circuit and the 

current moves through the path with the least resistance. The current then flows to the 

different connected appliances. The major advantage is that if there is a break in one 

of the branches, current can still flow. For example, if a light bulb burns out, 

current can still flow through the rest of the lights and plugs. 

History 

The invention of the battery by 

Alessandro Volta in 1800 made possible 

the development of the first electric circuits. 

A continuous flow of current was now possible. 

The very first circuits used a battery and electrodes 

immersed in a container of water. 

By 1847 Gustav Kirchhoff formulated laws dealing 

with conservation of charge and energy 

in electric circuits. 


Figure 1: Puzzle Circuit 

Figure 2: A Parallel Circuit 

The electric wiring of a house is an example of a parallel circuit. 

Real life circuits are generally very complex combinations of series 

and parallel connections. This is especially the case for printed 

circuit boards (PC boards) of electronic equipment such as computers. 


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Try this Out! 

Today very complex electronic circuits that contain several transistors 

and resistors can fit on a single silicon chip. These integrated circuits 

(IC’s) make today’s computers possible. 

You will need one or two 1.5V (AA or AAA) 

torch batteries, two torch globes, and some 

thin insulated electric wire. Try to construct 

a parallel electric circuit and put one globe 

in each branch. 

If correctly connected, both globes should 

light up. Now disconnect only one of the 

branches. The other globe should still glow. 

Try making three branches using three globes. 

Can you draw the circuit diagram of all 

the circuits that you have constructed? 

Figure 3: A Circuit Board 


Electricity Travels Through 

My Body 

Figure 1: Electricity Travels Through My Body 

Figure 2: A scale that measures body fat 

The Exhibit 

Figure 3: Nicola Tesla using his body to conduct electricity 

A number of visitors hold hands to form a closed 

circle with the exhibit. A light shines to show that 

electricity has travelled from the exhibit through 

each participant. 


Body fat scales are used to measure the amount 

of body fat in a person. This is done by sending 

electrical impulses up one side of the body and 

down the other. Fat molecules are non-polar in 

nature, and are a poor conductor of electricity. Lean 

muscle tissue utilizes micro electrical impulses 

from the brain to move and they also have a lot of 

ions, which makes them a good conductor of 

electricity. So the amount of body fat in a person 

can be determined by the conductivity of 

electrical currents. 

History 

In 1791 Luigi Alyisio Galvani 

discovered during experiment with 

static electricity that the muscles of dead frog legs 

will twitch if struck by a spark. He called this animal 

electricity and believed it came from electrical fluid 

inside the muscle. Galvani’s associate Alessandro 

Volta disagreed and reasoned that electricity was not 

biological but a physical phenomenon. He built the 

first battery, the voltaic pile, specifically to disprove 

Galvani’s theory. 


An electrocardiograph (ECG) is an 

instrument that measures the electric 

impulses coming from the heart. Sensitive 

electrodes are placed on certain parts of the body. 

A disruption in the transmission of the impulses 

through the heart’s electrical conduction system due 

to, irregular heartbeats or dead heart tissue will be 

detected by the electrode. The result is displayed on 

a graph, which can be used to make a diagnosis. 


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Figure 4: ECG electrodes on the body 

Try This Out! 


The Human body contains 

about 70 percent water and many 

electrolytes. This makes the body 

a good conductor of electricity. 

The degree of conductivity depends 

on factors such as the body fat percentage or how 

contact is made with the skin. Sweat and blood are 

excellent conductors of electricity because they are 

rich in salts and minerals. Electricity encounters 

much less resistance when it is in contact with wet 

or sweaty hands. 

It is estimated from an average figure of body 

resistance that about 20V can produce a current 

of 20mA, which is enough to produce 

a dangerous shock. 

Determine if some common liquids can conduct electricity! You can do this 

by using a multi-meter. Set the tester to measure ohms (resistance). 

Put the liquid to be tested into a beaker or cup. Test its conductivity by inserting both probes into 

the solution, ensuring that the probes do not touch each other. The higher the meter reading 

(in ohms) is the lower the conductivity of the liquid. 

Test the conductivity of distilled water, tap water, a salt-water solution, a sugar-water solution, 

vinegar, lemon juice, a soft drink and milk. Record the results in a table and compare the 

conductivities of these liquids. The more ions a liquid contains the easier electricity will 

be able to flow through it. 


Feeling Electricity 

Figure 1: Feeling Electricity 

The Exhibit 

In the exhibit, a mild electric current is produced 

by means of turning a handle of a generator. 

Visitors can feel this electric current in the form 

of a mild electric shock when the two metal 

buttons are touched. 


Why are birds not electrocuted when sitting 

on power lines? Does electricity not travel 

through them or are their feet insulators? 

Bird only sits on one power line, so there is 

no complete circuit for the electricity to pass 

through. Therefore, the bird does not get 

electrocuted. Also the bird’s electrical resistance 

is much greater than the power line and therefore 

very little current will flow through it. 

History 

Thomas Edison endorsed the use 

of the electric chair in 1888 as a 

mode of capital punishment. 

Electric torture has been used since the 1930s 

by repressive regimes and in warfare. 

Figure 2: A bird on a power line 

Another device that was intended to shock victims 

is the Electro-Convulsive Therapy (ECT) device, 

which was invented in the early 1930s by two Italian psychologists, Dr. Ugo Cerletti and Dr. Lucio 

Bini. This device is now used as a treatment method for some psychological disorders. 


Electricity can be sent through the body under controlled 

conditions for various uses. Electroconvulsive therapy is 

used commonly in psychiatry as a means of treating severe depression. 

The Transcutaneous Electrical Nerve Stimulator (TENS) is a device 

that uses low electrical currents to stimulate the nerves and 

relieve acute and chronic pain. Sticky pads are attached to the patient 

between the areas of pain and the patient is able to control how much 

current passes through them. The TENS unit is often used in 

different therapeutic and rehabilitation situations. 

Figure 3: TENS Unit 


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The human body’s nervous system uses electrical signals to receive 

information from around the body via sensory neurons. 

The messages from the sensory neurons travel to the brain where the appropriate response is 

initiated through motor neurons. The nerve cells in the body are made up of four main 

components: the dendrite, the cell body, the axon and the axon terminals. 

Neurons communicate with other neurons through action potentials. These are changes in the 

electrical potential of a cell through the influx and efflux of certain ions such as sodium and 

potassium. The signal is sent down the axon and to the axon terminals. Information transfer 

occurs at the synapses of the nerve cells (space between axons terminals to dendrites of another 

nerve cell). This structure transmits the electrical signal to another neuron using a chemical 

messenger called a neurotransmitter where it is able to initiate another electrical response. 

This process repeats moving toward the central nervous system to the brain. Once at the brain, 

and the appropriate decision is made, an electrical signal is once again sent down the body 

to the correct area using motor neurons to initiate the response. 

When you get a shock from an outside source of electricity, it interferes with the body’s 

electrical systems which causes your muscles to contract and then relax rapidly. 

Too much electricity may cause burns, ventricular fibrillation (heart stops beating) and 

maybe even some neurological problems. 

Try This Out! 

While wearing socks, drag your feet 

for about 5 minutes on a carpet. 

Now touch a metal surface or another 

person. What do you feel? This is electricity 

moving from your fingers to another object. 

Figure 4: Nerve cell Synapse 


Bright Lights 

The Exhibits 

The exhibit consists of vehicle headlamps 

connected to a lever switch that is connected 

to a column of a steering wheel. When the lamps 

are switched on, the lever switch may be pushed 

down to make the lamps shine brighter. 


Vehicle headlights play an important role in road 

safety because it needs to be designed in a way 

to ensure the light does not blind incoming drivers 

while keeping the road ahead well illuminated. 

The modern vehicle headlamp system is capable of 

producing two types of light beams. High beams, called 

“Brights” in South Africa, cast most of the light straight 

ahead, but offer little control of the light being directed 

at incoming drivers eyes’. 

Bright lights are only suitable to use when there are no 

other vehicles approaching, as the glare they produce 

will daze incoming drivers. 

Low beams (or dims) are used for normal driving when 

there are other drivers on the road. The light is distributed 

to provide adequate front and side illumination 

while controlling glare. The light beam they produce 

contain a sharp asymmetric cut off which prevent 

significant amount of light being casted into the eyes of 

incoming drivers. They are intended for use when there 

are other drivers ahead. 

Dual-filament light bulbs are capable of producing 

both the high and the low beams. The high-beam filament 

is placed at the focal point for best illumination 

of the road (Figure 4). The low-beam filament is placed 

slightly off the focal point to produce the asymmetrical 

cut of the light. Some lamp systems also use a metal 

shield to provide this cut-off pattern. 

Figure 1: Bright Lights 

Figure 2: Low Beam (Dims) Illumination. 

Figure 3: High Beam (Brights) Illumination. 


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History 

The first headlamps for vehicles were introduced in the late 1880s. These were 

flame lamps and fuelled by acetylene or oil. The first electric lights were introduced 

in 1898. “Low beam” lamps were introduced in 1915; however this required the driver to get out 

of the vehicle to adjust the lamp, which was tiresome and sometimes problematic. In 1917, 

levers were added which allowed the lamp to be turned on from inside the vehicle. 

The first halogen headlamps came around in 1962 and High Intensity Discharge (HID/xenon) lamps 

were introduced in 1991. Since 2004, there has been active development in headlamp applications 

using Light Emitting Diodes (LEDs). 


Headlamps are used on a variety of vehicles. 

The designs have varied over the years due to advances 

in technology, as well as introduction of new regulation 

regarding headlamp usage. Originally, headlamps are only used for 

nighttime driving or during periods of low visibility on the road. 

In recent years they are also being used during the daytime to increase 

the vehicle’s visibility to other drivers. 

The latest advance in technology is the use of adaptor headlamps. 

Here the headlamp beam turns as the vehicle goes around a curve 

to give a better view of the road ahead. The amount of glare is also 

reduced because these headlights are always directed at the road. 


Figure 4: A quartz-iodine 

lamp with 2 filaments. 

Three basic types of optics are used in vehicle headlights. These are: 

1. Lens Optics. These use a light source, a reflector and a lens. The lens is molded on to the front of 

the headlamp and bends the high beam via Fresnel optics towards the road surface, reducing glare. 

2. Reflector Optics. In these systems, reflectors made out of multiple mirrors are used to reflect the 

light towards the road surface. 

3. Projector Optics. These systems uses ellipsoidal reflector instead of the normal parabolic 

reflector. A condenser lens is placed at the front of the headlamp to focus and direct light. 

A shield placed near the imaging plane is used to produce a low and a high beam of light. 

Try This Out! 

If you don’t already know, ask someone to show you where the headlamp switch 

in the vehicle is. Let them show you how the vehicles bright lights are switched on. 

Look at the headlamps of a vehicle and see if you can determine what type of optics are being used. 

Figure 5: Lens Optics. Figure 6: Reflector Optics. Figure 7: Projector Optics. 


The Filament in the Light Bulb 

The Exhibit 

Visitors are able to increase the current flowing 

through a light bulb and see the filament’s 

change in temperature on a thermometer. 


Whenever an electron jumps from a higher energy 

state to a lower energy state, it emits a photon. 

The energy (wavelength) of the photon depends on 

the energy difference between the higher and lower Figure 1: The Filament in the Light Bulb 

state. A photon’s “color” is determined by this energy. At normal room temperatures, 

emissions of these photons are quite common, but the photons are not energetic enough to be in 

the visible light spectrum. The least energetic color we can see is the wavelength of the color red. 

Longer wavelengths are referred as “infra-red”, that is why infrared goggles work as they detect 

wavelength of the photons in the infrared range. 

History 

While experimenting with 

electricity in 1800,Humphry Davy, 

an English scientist, made the 

first electric light. He had 

connected a piece of carbon 

paper to a battery he invented 

and the carbon glowed, 

producing light. In 1860, 

Sir Joseph Wilson Swan 

improved on the carbon filament 

and enclosed it in a vacuum in 

order to avoid blackening of the 

bulbs from reactions of the 

filament with some gasses. 

Thomas Alva Edison, 

Figure 2: Electro Magnetic Spectrum 

an American inventor, 

experimented with thousands of filaments in order to find the material that 

glowed well and was long lasting. Edison eventually (in 1880) produced 

a bulb that glowed for over 1500 hours. It was William David Coolidge who, 

in 1910, invented a tungsten filament that lasted even longer than the 

other filaments. 


Incandescent light bulbs come in a variety of sizes, light output and voltage 

ratings. They range from 1.5V to 300V and can be used with AC or DC 

supply. They are widely used in lighting household and commercial spaces, 

for decorative lights and advertising lighting. 


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They can be used in portable applications such as lamps, torches and cars. Applications such as 

incubators, brooder boxes and reptile tanks take advantage of the heat generated by the filament. 

Their greatest disadvantage is that they are not very energy efficient. About 90% of the power 

consumed is emitted as heat and only 10% as light. The heat given off also increases the energy 

required by a building’s air conditioning system. Incandescent bulbs are now gradually being 

replaced by fluorescent lamps and high-intensity discharge lamps and light emitting diodes, 

which are much more energy efficient 


When current flows through the filament of the light bulb, the atom 

in the filament gets excited and the electron moves to a much 

higher energy state. As the electrons retrun to a lower energy state, 

they emit photons in the visible spectrum. The filament also heat up to 

a very high temperature. Most of the metal at this temperature will melt, however, Tungsten has a 

very high melting temperature and thus it does not melt while emitting visible light. 

Since the metal is at a very high temperature, it excites the gas molecule surrounding it, 

especially oxygen, which will react readily (explosion!). For this reason, incandescent light bulbs 

are made out of tungsten filament which is surrounded by an inert gas (such as argon), 

to prevent combustion. 

Try This Out! 

Make your own light bulb 

You will need: 

1. A small glass jar with a 

cork lid. 

2. A small nail. 

3. 90cm of insulated copper Figure 3: Light bulb set up 

wire. 

4. A 6-volt battery. 

5. Thin iron wire (e.g. unraveled picture hanging wire). 

Remember if this wire is not thin enough with a high 

enough resistance, it will short circuit the battery. 

6. Pliers for cutting and stripping wire. 

Figure 4: The incandescent light bulb 

Procedure: 

1. Cut the copper wire into two lengths. Cut off about 2½cm of insulation from each end 

of each length of wire. 

2. With the nail, make two holes in the cork. Push the lengths of wire through the holes 

in the cork so that you can see about 2cm of wire in the jar. 

3. Make a hook at the end of the copper wires that will go in the jar. 

4. Twist several strands of iron wire together and stretch them across the gap between 

the two copper hooks to make your filament. 

5. Put the filament and cork stopper inside the jar. 

6. Carefully connect the other end of the copper wire to the 6V battery and 

watch your bulb light up! Do not touch the filament – it is hot! 

Monitor the battery to check that it does not get hot. 

7. Note the time your filament will last and then try with different numbers of iron wire strand. 

Record your results. 


When the Current Flows, 

Things Heat up 

The Exhibit 

The exhibit consists of two different lengths 

of wire connected to an electric generator. 

Visitors turn the generator handle to produce 

electricity which passes through the wires and heats 

them up. The wires glow when heated. 


An incandescent light bulb contains a fine filament 

wire, usually tungsten, in a gas-tight glass 

container. When a current passes through the 

filament, it heat up. It reaches a very high 

temperature and eventually gives off energy in the 

form of light. Contained in these bulbs are noble 

gases such as argon which are inert and help the bulb 

last longer. In incandescent bulbs, about 10% of the 

energy is used to create light while the rest is in the 

form of heat. 

History 

Figure 1: When the Current Flows Thing Heat up 

In 1802, an English chemist, 

Figure 2: Electrical Resistance 

Sir Humphrey Davy, conducted an 

experiment where he ran electrical current through a thin strip of platinum. 

In essence, this marked the beginning of the incandescent light bulb. With this experiment, 

he showed that it is possible to run an electric current through a certain metal to generate light. 

Joule’s first law (sometimes called Joule-Lenz law) expresses the relationship between heat 

generated and the current flowing through a conductor. If there is an increase in the amount 

of current flowing through a conductor, the amount of heat generated due to resistance also 

increases. It is named after James Prescott Joule and Heinrich Lenz who discovered 

it independently in the 1840s. 


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Electric heating is widely used to cook food, heat rooms and boil water and 

in different industrial processes. 

Electrical heating is seen as a more efficient source 

of energy because it is 

better controlled and monitored. It is also more beneficial 

to the environment 

since process is usually much cleaner. 

The main drawbacks are its higher costs of 

operations compared to direct use fuels, the capital 

costs of heating apparatus and the infrastructure 

needed to deliver the electrical energy. 

Figure 3: A Fuse 

The wire of a fuse is designed to melt, and therefore break the circuit once the current goes the 

fuse’s melting point. Fuses can therefore be used to protect equipment or appliances from large, 

unexpected currents (overloads). 


When current flows through a wire, some of the electrons collide 

with the atoms of the metal conductor. The metal conductor heats up 

as some of the kinetic energy from the electron is transferred to the 

atoms, making them vibrate faster. Temperature is a measurement 

of the amount of kinetic energy in a particle. This is known as the 

electrical resistance which is opposition to the passage of an electric current through that 

element. The resistivity of each material depends on the physical property of the material, 

wire size, and the amount of current running through the wire, and it is measured ohms. 

Try This Out! 

Compare the heat given off from a compact fluorescent light bulb and an 

incandescent light bulb. 

Caution: Do not touch the bulbs but place you hands near them to feel the heat. 

What is the difference? Why? 


Vehicle Indicators 

The Exhibit 

The exhibit is made up of a steering wheel, 

an indicator lever switch, a flasher unit and 

left and right indicator lights. Visitors are able 

to move the lever switch up and down so that 

the left and right lights flash. 


The flashing of indicator lights is made possible 

through the flasher unit. This system uses a hot 

Figure 1: Vehicle Indicators 

bimetallic strip to control the indicator lights. 

The hot bimetallic strip contains two different 

metals which expand at different temperatures. The strip is able to bend in one direction if heated 

by an electrical current and bend in the other direction if cooled. This happens because the metals 

in the strip have different thermal expansions which mean that they expand and contract at 

different temperatures. As the strip bends, it closes the circuit and causing the indicator light 

to switch on. The strip then cools down and straightens, moving away from the contact. 

This causes the circuit to open again which makes the indicator light to switch off. This on and off 

cycle produces a flashing light. 

Bi-metallic Strip or Spring 

History 

Electric turn signal lights were 

invented in 1907. Previously, 

hand signals were used to indicate that one is 

going to turn; but these are now only used when 

the indicator lights are not working. It is now a 

requirement in most countries that vehicles 

are fitted with electric indicators. 

Most vehicles have a mechanism that 

automatically moves the lever to the “off” 

position after you make a turn. Indicators are 

now also put into the side mirrors of vehicles 

to help other motorists next to you see 

your signals. 

Upon heating: 

metal 2 expands 

more than metal 1 

Upon cooling: 

metal 2 contracts 

more than metal 1 

Figure 2: Bimetallic Strips 

Figure 3: 

Dashboard Turn 

Signal Indicators 


ME 21/11/12 V7 

1 2 

2 

1


Bimetallic strips are also used in other applications such as 

in mechanical clocks to compensate for changes in temperature 

in the clock’s internal mechanism. Therefore, this allows for accurate 

timekeeping. They are used in thermostats, electric kettles, 

air conditioners and refrigerators to automatically switch the appliance 

on and off and in circuit breakers to protect circuits from excess current 

or from short circuiting. 

Try This Out! 


Flasher units are not only made of the bimetallic strip system 

but also electromagnets and electronic timer chips. 

Try and find out how these systems work. 

If you don’t already know, find out where the indicator switch in a vehicle 

is located. The clicking sound you hear is the flasher unit switching on and off. 

In modern cars, a digital sound is usually used to imitate the sound of a flasher unit. 


The More Lights you Switch on 

the More Current you need 

Figure 1: The More Lights you Switch on the 

More Current you need 

Figure 2: Measuring elecricity usage 

in Kilowatt-hours 

Figure 3: Faraday’s Disk Generator 

The Exhibit 

Visitors can select one to five parallel light 

bulbs and turn a generator handle to get them to 

light up. The more light bulbs they select the more 

they have to turn the generator to get them to glow 


Electricity is measured in units of power called 

Watts (W), or more commonly kilowatt (kW, 

or kVA), which is equals to 1000 watts. 

The higher the kilowatt rating of an electrical 

appliance, the more electricity it requires to run, 

and the more energy it consumes. 

The amount of electricity we use over a period of 

time is measured in kilowatt-hours (kWh), which is 

the amount of kW multiplied by the hours of use. 

History 

A viable source of electricity became 

available when Alessandro Volta 

invented the voltaic pile (an early, 

primitive battery) in 1800. 

Electro-mechanical generators are used to produce 

electrical current using the principle of electromagnetic 

induction by moving a conductor through 

magnetic field. The movement of the conductor 

driven by mechanical or thermal energy from fossil 

fuels such as coal and crude oil, nuclear reactors, 

or from sources such as wind, flowing water or 

solar energy. The modern steam turbine was 

invented by Sir Charles Parsons in 1884 and 

was based on Faraday’s disk generator of 1831 

which is credited to be the first electric generator. 

These steam turbines were implemented in 

different types of marine transport vehicles. 



ME 21/11/12 V7

Electrical power is the backbone of modern industrial society. It is very versatile 

and flexible and has an almost limitless set of applications. 

These include transport, heating, lighting, computation and communications. 

There is now an increased focus on generating electricity from renewable sources like wind, 

hydropower and solar power due to the environmental concerns of generation from fossil fuels. 

Byproduct of burning fossil fuel is the production of greenhouse gases, which accelerate 

the effects of global warming, as well as damaging the ozone layer. 

Try This Out! 


When you switch on more lights you are increasing the load of the 

circuit. When the supply voltage is the same, then you need to draw 

more current to keep the lights burning. 

Locate the electricity meter of your home. Switch off as many appliances 

as you can. Take note of the speed of the meter (amount of units per minute). 

Now switch on one room light at a time and record the speed after each light is switched on. 

What do you notice? Compare your monthly electricity consumption with those of your friends. 

Do the same with the water meter and open the tap slowly and then faster. Compare the speed 

of the water meter each time. Compare the flow of water to that of electric current. 


Ohm’s Law Demonstrator 

The Exhibit 

Visitors select two values from volts, amps 

or ohms and use the demonstrator to 

calculate the third one. 


Georg Simon Ohm’s father was a locksmith who 

was very well educated; he taught his children 

mathematics, physics, chemistry and philosophy Figure 1: Ohm’s Law Demonstrator 

before they entered school. During his studies, 

Georg Ohm received very little scientific training; instead he spent much time dancing, ice-skating 

and playing billiards. His father was quite displeased at him for wasting his youth, took him out of 

the university, and sent him to Switzerland. 

In Switzerland, He accepted a position as a schoolteacher in mathematics and continued his 

studies on his own in 1806. He later returned to the University of Erlangen in April 1811 and 

received a doctorate in mathematics on 25 October 1811 because of his private studies. 

When he published his famous law it was met with much resistance. Many of his countrymen 

considered voltage and current to be separate entities. The Prussian minister of education even 

made the announcement, “a professor who preaches such heresies is unworthy to teach science.” 

One science critic claimed that its “sole effort is to detract from the dignity of nature.” Eventually, 

he was recognized by the Royal Society of England and awarded the Copley Medal in 1841 with the 

inscription “he had clarified in a remarkable way what had been previously wrapped in mystery 

and confusion.” 

History 

In 1781, Henry Cavendish did a 

number of experiments with Leyden jars and 

glass tubes of varying diameter and length filled 

with salt solution. He noted how strong a shock 

he felt as he completed the circuit with his body 

and measuring the current at the same time. 

Cavendish concluded before Ohm did that the 

current varied directly as the “degree of 

electrification” (voltage) varied. His results 

were largely unknown and only published in 

1879 by Maxwell. 

Figure 2: Ohm’s law illustrated in a stamp 

Georg Ohm published his experiments and his complete theory on electricity in the book 

Die galvanische Kette, mathematisch bearbeitet (The galvanic circuit investigated mathematically) 

in 1827. The work of Ohm marked the early beginning of the subject of circuit theory, 

although this did not become an important field until the end of the century. 


ME 21/11/12 V7


Ohm’s law is one of the basic equations that are used to analyze electric circuits. 

It is used for practical computations of voltage, current or resistance. 

The relationship between voltage (V), current (I) and resistance (R) is represented 

by a triangle to ease calculations. The vertical line represents multiplication and 

the horizontal line represents division. Ohm’s law may be combined with Joule’s law to calculate 

the power dissipated by a resistor. 

Figure 3: Ohm’s law & Joule’s 

law relationships 

The ohm (symbol: Ω) is the SI unit for electrical resistance. 


Ohm’s law states that the flow of current is directly proportional to the 

applied voltage and inversely proportional to the resistance of the 

circuit. Thus the relationship between voltage, current and resistance 

can be formulated mathematically as: 

V is the voltage, I the current and R the resistance. 

An element (resistor or conductor) that obeys Ohm’s law is known as an ohmic device. 

Some circuit elements like capacitors or diodes do not directly obey Ohm’s law and are 

called non-ohmic devices. 

Try This Out! 

You can verify Ohm’s law. You will need: 

• A 100 ohm, 200 ohm and 300 ohm resistor 

• An ammeter and a voltmeter or a multimeter 

• A 9 V battery 

• Wires to connect to battery terminals 

Method 

1. Connect a circuit, as shown in the figure, using the 100 ohm resistor. 

“A” is the ammeter position and “V” the voltmeter position. 

2. Measure and record the current with the ammeter and voltage 

with the voltmeter. 

3. Repeat with the 200 and 300 ohm resistors. 

4. Show that in all three cases V = I x R. 

Figure 4: Experiment 

set up 

Plot the graph of I vs. 1/R two show that the current is inversely proportional to the resistance 


More Batteries Please! 

Figure 2: Batteries in Series 

The Exhibit 

The exhibit consists of four batteries, a model 

train, a light and a buzzer. The correct amount 

of batteries must be used and they must be 

connected in the correct polarity to make 

the train, light and buzzer work.. 


The voltage rating of a battery is its nominal open 

Figure 1: More Batteries Please 

circuit voltage, which is difference in electrical 

potential between the two terminals when the 

battery is disconnected. The voltage rating also depends on the chemistry and the number of 

cells it contains. The capacity of a battery is its energy in ampere-hours (Ah). 

When two batteries of the same voltage are connected in series the voltage is doubled but the 

capacity rating (amp hours) remains the same. When these are connected in parallel the capacity 

is doubled but the voltage remains the same. These are important properties of series and 

parallel circuits. 

Figure 2: Batteries in Series 

History 

Figure 3: Batteries in Parallel 

Figure 3: 

Batteries in Parallel 

Alessandro Volta built the first battery in 1800 by piling layers of copper, 

cloth soaked in salt and zinc. This Voltaic pile could not deliver currents for 

long periods of time. 

The Daniel Cell developed in 1820 by John Frederich Daniel was able to overcome this problem. 

These were wet cells that used zinc and copper sulphate solutions as electrolytes. But they were 

fragile, prone to leakage and were unsuitable for portable applications. 

Raymond Gaston Planté developed the lead-acid battery in 1859 by rolling up two strips of lead 

sheet separated by pieces of flannel and immersing them in dilute sulphuric acid. It was the 

earliest form of rechargeable battery, and lead-acid is still in use today. 

The first dry cell battery was developed in 1866 by Georges Leclanché. These cells made use of 

a paste instead of a liquid as an electrolyte, thus greatly improved the portability of the battery. 

Thomas Edison developed the alkaline cell between 1898 and 1908 using a nickel-iron system. 


ME 21/11/12 V7


Batteries can be used as single cells to deliver power to cell phone, 

laptops and other portable electronics. They can also be connected in 

series to deliver several hundreds of volts as in uninterruptible power 

supplies (UPS). In recent years, advancement in technology has allowed 

the usage of battery to power electric cars. 

The world’s smallest battery has been developed at Rice University in Houston Texas by means 

of packing a battery into a nanowire. It is 6 times thinner than a bacterium (0.2-2 microns), 

100 times thinner than a human hair (200 um) and 60 000 times smaller than an AAA battery. 

Large arrays of batteries are used to store the energy derived from renewable power sources such 

as wind turbines and solar-cell systems. A 30-megawatt (MW) wind farm uses a storage battery 

that is equivalent to 20 000 car batteries. 1MW will power 50 households. 


Compared to other power sources, batteries are best suited 

for portable and stationary systems. For applications such as trains, 

ships and aircraft, the battery lacks capacity, endurance and reliability. 

Some of the positive traits of batteries are: 

• Store energy well for a considerable length of time. 

• Hold enough energy for portable use. 

• Quickly deliver energy on short notice. E.g. a camera’s flash. 

• Have a wide power range. 

• Do not exhaust toxic gases. 

• Highly efficient. 

• A sealed battery can operate in any position and has a good shock and vibration tolerance. 

• Operational costs vary with battery type. 

• Rechargeable batteries require low maintenance. Others might require cleaning of terminals and 

performance checks. 

Some of the negative traits of batteries are 

• Rechargeable batteries have a relatively short service life. 

• Cold temperatures slow their performance and high temperatures cause rapid aging. 

• Long recharge times. 

• Contain hazardous materials such as heavy metals and cannot be disposed in landfills. 

It is recommended that they be recycled. 

Try This Out! 

You will need a toy car or train that works on batteries. Try connecting one of its batteries 

to the toy with thin electric wire. Make sure the positive and negative terminals of the battery 

are connected to the right places in the battery compartment. Notice the speed and direction 

the wheels are turning. Now reverse the connections at the battery terminals. 

What happens to the wheels? 

Repeat this with two batteries connected in series. What happens to the speed of the wheels? 


Selecting the Right Battery 

The Exhibit 

Two cable ends are used to connect different 

size and voltage batteries to a merry-go-round. 

Visitors are shown that the voltage of the 

battery is more important than its size 

or shape. 


The amount of potential energy stored in 

Figure 1: Selecting the Right Battery 

a battery depends on the type and the 

amount of materials used in its construction. For example, an alkaline battery has about four 

times the energy than a zinc-carbon battery of the same size. Different chemicals will produce 

different potentials due to their ability to donate or accept electrons during the redox reaction 

that takes place in the battery. The more energy a battery has, the greater the amount of voltage 

it can supply to an appliance. 

The same size battery (AA) can have different amounts stored energy. 

Table1: Energy Storage in AA Batteries 

Battery Type Avg. Voltage milli-Amp hours (mAh) Watt-hours (Wh) Joules (J) 

During Discharge 

Alkaline 1.225 2122 2.60 9360 

Long-life 

Carbon-zinc 1.1 591 0.65 2340 

Nickel-Cadmium 1.2 1000 1.20 4320 

NiMH 1.2 2100 2.52 9072 

Lithium Ion 3.6 853 3.1 11050 

History 

The table below shows a brief history of the development of the battery. 

Table 2: Battery Advancements 

Year Inventor Activity 

1600 William Gilbert (UK) Establishment of electrochemistry study 

1791 Luigi Galvani (Italy) Discovery of “animal electricity” 

1800 Alessandro Volta (Italy) Invention of the voltaic cell (zinc, copper disks) 

1802 William Cruickshank (UK) First electric battery capable of mass production 

1820 André-Marie Ampère (France) Electricity through magnetism 

1833 Michael Faraday (UK) Announcement of Faraday’s law 

1836 John F. Daniell (UK) Invention of the Daniell cell 

1839 William Robert Grove (UK) Invention of the fuel cell (H2/O2) 

1859 Gaston Planté (France) Invention of the lead acid battery 


ME 21/11/12 V7

Year Inventor Activity 

1868 Georges Leclanché (France) Invention of the Leclanché cell (carbon-zinc) 

1899 Waldmar Jungner (Sweden) Invention of the nickel-cadmium battery 

1901 Thomas A. Edison (USA) Invention of the nickel-iron battery 

1932 Shlecht & Ackermann (Germany) Invention of the sintered pole plate 

1947 Georg Neumann (Germany) Successfully sealing the nickel-cadmium battery 

1949 Lew Urry (Canada) Invention of the alkaline-manganese battery 

(Eveready ttery) Ba 

1970s Group effort Development of valve-regulated lead acid battery 

1991 Sony (Japan) Commercialization of lithium-ion battery 

1994 Bellcore (USA) Commercialization of lithium-ion polymer 

2002 University of Montreal, Improvement of Li-phosphate, nanotechnology, 

Quebec Hydro, MIT, othersa commercialization 


Common primary cell batteries (disposable) have voltages that range from 1.5V 

to 3.0V. These are used in portable mp3 players, alarm clocks, watches and 

much more. Secondary or rechargeable batteries are more commonly used 

in iPods, cars, generators, and cell phones. 

A good battery must be able to provide adequate voltage and current needed during usage. 

They must also be able to retain the stored energy for some time. It should be economical, 

readily replaced or easily rechargeable. 


A battery’s capacity is the amount of electric charge it can store. 

The more electrolyte and electrode material there is in the cell, the greater 

the capacity of the cell. A small cell has less capacity than a larger cell with 

the same chemistry and they develop the same open-circuit voltage. 

Because of the chemical reactions within the cells, the capacity of a battery depends on the discharge 

conditions such as the magnitude of the current (which may vary with time), the allowable 

terminal voltage of the battery, temperature and other factors. The available capacity of a battery 

depends upon the rate at which it is discharged. If a battery is discharged at a relatively high rate, 

the available capacity will be lower than expected. 

Try this Out 

You will need the following: 

1) A torch globe that can hold 3.0 V of power. 

2) Thin electric wire. 

3) A 1.5V battery 

4) A 3.0V batteryTry this Out (cont.) 

First connect the one end of the two wires to the connection points on the globe, 

usually on at the bottom and the other on the side of the globe. Now connect 

the other end of the wires to each terminal on the 1.5V battery. Observe the 

brightness of the globe. Repeat this with the 3.0V battery and observe what happens. 


The Current Only Flows when 

the Appliance is Connected 

to a Battery 

The Exhibit 

The exhibit consists of a battery and three 

appliances. Visitors connect each appliance to the 

battery to make it work. All three appliances may 

be connected to the battery at the same time to 

show that the current decreases. 


Batteries are chemical cells that store electrical 

energy. Through the process of redox inside the 

battery, electric current is generated and electron 

flows from the negative terminal of the battery to its 

positive terminal through a circuit. This is the process 

of converting potential chemical energy into 

electrical energy. 

History 

Figure 1: The Current Only Flows when the 

Appliance is Connected to a Battery 

The work of Michael Faraday, 

Figure 2: Electron Flow in a circuit 

Luigi Galvani, Alessandro Volta, 

André-Marie Ampère and George 

Simon Ohm built the foundation for the advancement of modern electrical technology. In the late 

1870s, the American inventor, Thomas Alva Edison, developed and built one of the first electricity 

generating plants and became the world’s main builder of direct current (DC) systems. 

Volta showed that electric power could be made to travel from one place to another. In 1800, 

he constructed the first device to produce a large electric current, called the battery. The first 

generator to produce alternating current was a dynamo generator developed in 1832 by Hippolye 

Pixii using Michael Faraday’s electromagnetic induction principles. Later, Nikola Tesla, 

a Serbian-American inventor, developed the modern AC power system. 


Everything that uses batteries runs on direct current (DC) while the electrical 

wiring of a house runs on alternating current (AC). DC is a constant streaming 

of charges moving in only one direction whereas in AC, the charges oscillates 

and change direction. 

AC electricity is used to carry power over long distances because you can use high voltages 

with small currents in order to reduce losses of energy by transmitting power. It is also easier and 

cheaper to make appliances that use AC electricity. The current of AC electricitycan also be 

increased and decreased easily through the use of a transformer. 


ME 21/11/12 V7


The symbol for current is “I” and its 

units are Ampere (A) named after 

André-Marie Ampère. The current in 

a circuit can be measured using an 

ammeter. By convention, current flow 

is the movement from a high potential 

(positive) to a low potential (negative). 

However, electron movement in the circuit is opposite to this 

(negative to positive). 

Try This Out! 

Figure 3: AC Power Lines 

Get two torch batteries (AA), two torch globes and some thin electric wire. 

Connect the contacts on the globe (one at the bottom and the other on the side) 

to each other with the electric wire. What happens? Why? 

Now connect the batteries in series. Connect the terminals of the battery pack to the 

contacts on the globe. Notice the brightness of the globe. 

Now connect the second globe in series in your circuit. What happens to the brightness 

of your globes? What has caused this? 


A Short Journey into Electricity 

The Exhibit 

The exhibit is an interactive audiovisual 

presentation on topics in electricity. It covers: 

• Electricity in the air 

• Electric current 

• Heating and lighting 

• Electromagnetism 

• Electrolysis 

• The battery 

• The light bulb 

• The electric motor 


Figure 1: A Short Journey into Electricity 

Some interesting electricity facts: 

• A single lightning bolt has enough electricity to service 200 000 homes during the strike 

• Mary Wollstonecraft Shelly wrote the book Frankenstein in 1818 after learning about Luigi 

Galvani experiment with frogs’ legs and electricity 

• Electrocution is one of the top five causes of death in the workplace 

• An electric eel can produce an electric shock of 650 volts at 1 ampere 

• The first electric chair was developed by employees of Edison’s company to prove that alternating 

current (AC) is more dangerous than direct current (DC) in the war between AC and DC 

•Our brain uses electric signals to communicate with our body 

•Electricity can magnetize certain materials 

History 

Some important dates in the history of electricity: 

• Static electricity was known in ancient Greece by rubbing amber which then 

attracted fibres and produced small sparks. Interestingly the word “electron” is derived 

from the Greek word for amber 

• In the late 1600s Otto von Guericke of Germany created a machine that could produce 

surface charge 

• In 1729 Stephen Gray discovered which materials could conduct electricity 

• In 1752 Benjamin Franklin proposed that electricity had positive and negative elements 

• In 1800 Alessandro Volta invented the first battery 

• In 1831 Michael Faraday linked electricity and magnetism 

and discovered electromagnetic induction 

• In 1879 Thomas Edison invented a long lasting electric 

light bulb 

• In 1885 George Westinghouse develops and uses 

Alternating Current 

• In 1888 Heinrich Hertz discovers electric waves and 

the means to measure them 

• In 1889 Nikola Tesla invents the Tesla coil and 

develops the first real AC motor 

Figure 2: A Tesla coil 


ME 21/11/12 V7


Electricity is one the most important and versatile sources of power. At home it powers 

all sorts of things like lights, air conditioners, televisions, etc. Batteries are portable 

sources of energy that produce electrical current to power devices like cell phones, laptop 

computers, and cameras. Even vehicles use electricity. For example, a battery starts the vehicle’s 

engine, which then generates electricity for use elsewhere in the vehicle. 

The generation of electricity from fossil fuels has led to concerns about the harmful effect on the 

environment in the form of greenhouse emissions. There is an increased focus on its generation 

from renewable sources such as wind, hydropower and solar power. 


There are many concepts used when discussing electricity. 

Some of the common ones are: 

Electric charge–This is the property of matter, which causes it to 

experience a force when it is near another charged object. It originates 

in the atom. There are two types of charge: positive and negative. 

The amount of charge is measured in coulombs [C]. 

Electric fi eld – It is the space surrounding an electric charge which exerts a force 

on another charge. As the distance from the charge increases, the force decreases. 

Electric current – A fl ow of electric charge passing a point in the circuit over a given amount 

of time. It is usually carried by electrons and is measured in amperes [A]. 

Electric potential – Is the energy that is needed to move a charge between two points. 

It is measured in volts [V]. 

Electric circuits – In an electric circuit, charge is made to fl ow along a closed path between 

interconnected components and usually performs some useful work. 

Try This Out! 

Infl ate a balloon and rub it on a woolen piece of 

clothing or on your hair. Hold it next to a wall and 

see what happens. If done right, the balloon will 

stick to the wall. 

A similar experiment can be done by running a comb through your 

hair to charge the comb with static electricity. This will allow the 

charged comb to attract pieces of tissue or paper. 

Try putting this charged comb near a fi ne stream of water 

running from a tap. Notice how the water bends. 

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Copyright Sci-Bono Discovery Centre 2012 ME 21/11/12 V7 31 

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Figure 3: A Charged Balloon

Beware of a Short Circuit 

Figure 1: Beware of a Short Circuit 

Figure 2: Fuse and Circuit Breaker 

The Exhibit 

In the exhibit, the terminals of a battery can be 

connected to a motor or made to touch each other. 

When they touch, a short circuit is made and 

a buzzer sounds as a precaution. 


In September 2010, There was an accident 

involving a Honda Jazz, after investigation, 

it was determined the cause was circuit defect 

in the power window switch. This led to Honda 

recalling its Jazz 2002 - 2008 models in South 

Africa at a high cost to the company. 646 000 cars 

were recalled by the company globally to fix the 

switch defect. 


Electrical circuits often include 

some protection against load faults 

like short circuits. Fuses and circuit 

breakers are two common means of protection. 

A fuse is piece of wire that becomes hot and melts when too much current flows through it. 

This causes a break in the circuit and stops the current. The fuse is sometimes put in a casing. 

Sometimes a circuit breaker is used instead of a fuse. The advantage of a circuit breaker is that 

it can be reset unlike the fuse where you need to replace it once it’s used. There is usually an 

electromagnetic coil inside the circuit breaker. When to much current flows through the coil, 

it pulls on a switch which then shuts the power off. The switch can be reset when the problem 

is rectified. Circuit breakers shut down the electricity supply to a house when someone has 

connected many appliances to one plug point or when an appliance has malfunctioned. 

History 

An American, Charles Grafton Page, invented the circuit breaker in 1836. 

The modern circuit breaker was patented by Brown, Boveri & Cie in 1924 and 

accredited the engineer, Hugo Stoltz. 

In 1847, French physicist, Louis-François-Clement Breguet recommended using smaller wires 

which would melt in case of a lightning strike, to protect apparatus inside telegraph stations. 

Thomas Edison patented a fuse as part of his electric distribution system in 1890. 


ME 21/11/12 V7


An electric short circuit occurs when current flows through an 

unintended path, usually a low resistance path, where there is no load. 

This can lead to excessive electric current or overload, which may 

cause circuit damage, overheating, fire or even an explosion. 

For example, when the terminals of a battery are connected together 

with a low-resistance wire, it will start delivering a large amount of energy 

in a short time. This causes a rapid buildup of heat, which could possibly 

causing an explosion releasing hydrogen gas and the battery’s electrolyte 

that can burn the skin, cause blindness or even lead to death. Also, 

damage to the wire’s insulation or a fire may also occur. In general-purpose, 

alternating current (mains) circuits, such short circuits could occur 

between two of the live, neutral or earth wires. Fuses or leakage devices 

are added to these circuits to protect against high currents. 

Short circuits may also lead to the formation of an arc, which may lead to 

fires. This arc is made up highly conductive, hot, ionized plasma. 

Damage done through the arc can be noted through surface erosion. 

Try This Out! 

Build a simple electric circuit using: 

• Wooden base to mount the circuit 

• 1 Light bulb (1.5V) 

• 1 Lamp holder 

• 1 D size battery holder 

• 1 D size battery 

• 1 Simple switch (known as knife switch) 

• Screws used to mount the switch and the lamp holder 

• Insulated solid copper wire (Gage 22) 

Figure 3: A burnt socket 

Set up the circuit as shown in Figure 4. Once you have built the 

circuit, activate the switch so that that bulb comes on. 

Figure 4: A burnt socket 

Now remove some of the insulation from the ends of a small 

length of insulated wire. Use the wire to touch the terminals of your lamp. 

The lamp should be extinguished. You have now bypassed the lamp creating a short circuit. 


Electricity Safety 

The Exhibit 

This is an audiovisual presentation on 

electricity safety. Three age groups are 

tested on identifying dangerous situations. 

They are 5 – 7 years, 8 – 10 years and 

11 years and above. 


Electricity has become an integral part of modern 

society, but under certain circumstances it can be 

fatal. It can damage sensitive equipment and 

ignite combustible materials. Most causes of Figure 1: The Electricity Safely 

deaths from electricity involve a voltage of 600V or less. 

A small light bulb rated 6 watts can draw a current of 0.05 amperes, which in some cases, 

can be fatal. “Figure 2” shows some effects of a current (in milli amps at 60Hz) passing 

through a 68 kg body. 


Where there is a dangerous electrical 

situation, warning signs are sometimes 

used to indicate the danger. Here are two examples: 

Figure 3: Electricity safety signs 

Figure 2: Effects of electric current on the body 

The Occupational Health and Safety Act 

(Act No. 181 of 1993) regulates conditions that 

are required in the workplace in order to protect persons against hazards to health and 

safety arising from activities at work. 


Electricity safety rules: 

• Do not use defective or unsafe electrical tools or appliances 

• Do not overload outlets with too many appliances 

• Do not play with electrical cords, switches or plugs that are attached to outlets 

• Always ensure that the power is off when repairing or cleaning an electrical appliance 


ME 21/11/12 V7

• Stay away from fallen power lines 

• Never use a hairdryer or other electrical devices near water. 

• Stay away from trees that are touching overhead power lines 

• Do not fly a kite near overhead power lines 

• Never climb electric utility poles or towers 

• Keep away from electrical sub-stations and transformers 

• Do not remove an appliance from the electric socket by pulling at the cord 

• Do not use electrical equipment outside when it is raining 

Common causes of unsafe appliances: 

• Loose connections 

• Faulty insulation 

• Inadequate grounding 

• Defective parts 

Potential hazardous situations involving electricity : 

• Flammable vapors, liquids and gases 

• Combustible dusts 

• Corrosive atmosphere 

• Explosive environment 

• Bad housekeeping such as excessive clutter, 

lack of proper hazardous signs, incorrect storage of 

flammable materials and unmarked electrical boxes 

• Wet or damp locations 

Response to Electrical Emergencies 

When someone else is experiencing an electric shock you should: 

• Not touch the person while they are being shocked 

• Keep others from being harmed 

• Report the incident 

• Shut off the power if you can 

• Use a non conductive item (eg wooden broom) to free the person 

• Give first aid if you are qualified to do so 

• Stay with the person until help arrives 

Try This Out! 

Figure 4: Electrical emergency 

Identify hazardous electrical situation at home and try to correct them or 

get someone to correct them. 

Find the substation that supplies electricity to you house. Note the different types of safety signs. 

Are they adequate? 


The Human Battery 

The Exhibits 

In these two exhibits an electric current is produced when one hand is placed on an 

aluminum plate and the other hand on a copper plate. In “Exhibit 1,” the current is 

measured by an ammeter and in “Exhibit 2,” it is indicated by the illumination of a lamp. 

If you increase the amount of moisture on your hands, the amount of current produced is 

also increased. 

Figure 1: The Human Battery (1) Figure 2: The Human Battery (2) 


The sweat from our hands is slightly acidic and contains many electrolytes; it is able to 

conduct electricity. Free electron flows from the copper plate to the aluminum plate as 

a result. The copper plate accumulates positively charges and the aluminum plate becomes 

negatively charged. This difference in charge results in the flow of current between the plates. 

Therefore, the human body acts like the electrolyte of a cell and also closes the circuit, 

thus allowing current to flow through it. 

History 

The Italian scientist, Alessandro Volta, developed a primitive battery in the early 

1800s called the voltaic pile. In 1836, John F. Daniell, an English chemist, 

produced a more efficient primary cell which contained two liquid electrolytes in order 

to produce a steadier current. Over the years, scientists have designed smaller but increasingly 

powerful batteries to suit our needs. For example, the small size of a lithium cell earned 

its name as a button cell battery; it is capable of producing voltages higher than any other 

type of cell. These are commonly found in small devices such as wristwatches and calculators. 


ME 21/11/12 V7


Batteries play an essential part of our daily lives, providing us with 

a mobile source of electricity. We use them in our alarm clocks, 

mobile phones, cars, etc. As of 2012, the fast charging and discharging 

batteries were the Lithium iron phosphate (LiFePO4), while the largest 

battery was developed in Fairbanks, Alaska and composed of Ni-Cd cells. 


A battery consists of one or 

more electrochemical cells 

that convert stored chemical 

energy into electrical energy. 

These cells are known as voltaic 

or galvanic cells. Each voltaic cell consists of two 

half cells that are connected in series by a 

conductive electrolyte containing anions 

(negative ions) and cations (positive ions). 

The diagram below illustrates a voltaic cell, which Figure 3: A Voltaic Cell 

has two half-cells linked by a salt bridge 

(the curved tube). This allows for the transfer for anions and cations. 

Try this Out! 

You can build a similar experiment at home. All you need is copper 

and aluminum plate, and a DC digital-ammeter with crocodile clips. 

The digital-ammeter can be obtained from your local electronics hardware store. 

Connect one of the digital-ammeter’s terminals to the copper plate using the crocodile 

clip. Connect the other digital-ammeter’s terminal to the aluminium plate using 

a crocodile clip. When you place your hands on each of the plates, the digital-ammeter 

should resister a reading. Try this experiment with your friends and family to see who 

conducts electricity the best. 


What is Inside a Battery? 

The Exhibit 

Visitors immerse two electrodes into a solution of water and 

vinegar. They will experiment on different combinations of electrodes 

made of copper, aluminum and stainless steel to see 

which produces electricity. 


A battery consists of one or more electrochemical 

cells connected together that are able produce electromotive 

Figure 1: The Exhibit 

force (EMF) from stored chemical potential energy. 

This is done through a process of reduction/oxidation or redox 

reactions. Electrochemical battery cells generally consist 

Figure 1: What is Inside a Battery 

of two linked half-cells, each with an electrode immersed 

in an electrolyte solution, and connected via a salt bridge. 

The negative electrode (anode) loses electrons through an oxidation reaction and the free electron 

flows to the positive electrode (cathode), thus the cathode is reduced. This flow of electron 

produces an electromotive force known as voltage. 

Electrons cannot flow just by themselves from one 

compartment to the other; this would create a charge buildup 

which would inhibit the flow of any more electrons. To solve 

this charge buildup, ions must be allowed to flow between the 

two components. This is the purpose of the salt bridge. 

History 

It is speculated from artifacts consisting of 

copper sheets and iron bars that galvanic 

cells were produced in ancient Bagdad. In 1792, 

Alessandro Volta developed the first electrochemical cell and 

by 1800 he built a crude battery by soaking small sheets of 

copper and zinc with cloth spacers in an acidic solution. 

Figure 2: An Electrochemical Cell 

These cells were not very reliable because their voltage fluctuated and could not provide 

a large current for an extended period. In 1836, a British chemist, John Frederic Daniell, 

invented the Daniel cell. These cells were a great improvement and used in the early days 

of battery development. 

Daniell cells are a type of wet cells; they were prone to leakage and spillage which made them 

unsuitable for portable appliances. Dry cell batteries were invented near the end of the 19th 

century which replaced the liquid electrolyte with a paste. This greatly improved the portability of 

batteries and proved to be very useful for a variety of operations. 


ME 21/11/12 V7


Batteries come in many sizes and types and are found in many 

types of applications. Hearing aids and wristwatches uses miniature 

batteries whereas cell phones, laptops uses larger battery packs, 

and cars rely on much bigger packs to ensure stable flow of 

current and voltage. 

The most common types of disposable batteries are zinc-carbon and 

alkaline batteries. Lead-acid batteries are one of the oldest rechargeable batteries, 

and are used commonly in modern vehicles. Other types of rechargeable batteries include 

nickel-cadmium (NiCd), nickel metal hydride (NiMH) and lithium-ion (Li-ion) cells. 

Modern day batteries have been developed with a built-in charger so that it charges 

when plugged into a USB port or any other power source. 

Try This Out! 


A battery is a collection of many electrochemical cells, but it is 

generally referred to as a single battery cell. Batteries are also 

classified into two categories: primary and secondary. 

Primary batteries can’t be recharged and typically loses 8-20% of their 

original charge every year when in storage; these are often referred 

as disposable batteries. Secondary batteries are typically rechargeable; 

however, they tend to deteriorate over time through cycles 

of charge and discharge. 

What you will need: 

a lemon; a strip of copper (or a copper coin); a strip of zinc (or a galvanized nail); 

a multimeter with two cables and crocodile clips; (optional) a thermometer or 

clock with an LCD display 

Instructions: 

1. Break up some of the sacks of juice inside the lemon 

by rolling the lemon firmly with your hand on a tabletop. 

2. Insert the two metal strips into the lemon without 

them touching each other, on the opposite sides 

3. Attach each clip of the multi-meter to the metal strips 

and measure the voltage of your lemon battery. 

4. If you do not have a multi-meter or if you want to see 

the battery working, connect the strips to a clock or 

thermometer that has an LCD display. 

Remove its batteries and connect your lemon 

battery to the clock or thermometer. 

Figure 3: The Lemon Battery 



Things are Electrolyzed 

Figure 1: When the Current Flows, 


Figure 2: Hydrogen from Water 


Electrolysis has 

many uses: 

•For the production of 

pure metals from their metallic 

The Exhibit 

The exhibit consists of two electrodes 

immersed in a solution of vinegar. Visitors pass 

a current through the electrodes by turning the 

handle of a generator. The resultant reaction is 

confirmed by the formation of gas bubbles 

at the electrodes. 


Hydrogen as source of energy that has about 

three times more energy than petroleum. 

The sun is a big ball of hydrogen gas that 

is undergoing fusion to helium and releasing 

vast amounts of energy.Hydrogen can be extracted 

from water through the process of electrolysis. 

Water is broken down into hydrogen and oxygen 

when an electric current is passed through it. 

This newly formed hydrogen may then be used as 

fuel cells for powering vehicles. It holds the promise 

for a virtually pollution free source of energy and 

independence from petroleum and fossil fuels. 

History 

A few weeks after Alessandro Volta 

(1800) invented the voltaic pile an 

early, primitive battery, William 

Nicholson and Anthony Carlisle used it by running 

a voltaic charge through water, splitting it into its 

hydrogen and oxygen components. Through this 

experiment, electrolysis was discovered. By 1869, 

the electrolysis of water became a cheap method 

for the production of hydrogen. In 1888, Dmitry 

Lachinov developed a method for the industrial 

synthesis of hydrogen and oxygen 

through electrolysis. 

compounds. For example, sodium metal can be made from sodium hydroxide. 

• Increasing thickness of oxide layers in metals (anodizing) to make them resistant to corrosion. 

Ships are anodized this way. 

• Recharging of batteries. 

• Electroplating of metals to fortify them for functional or decorative purposes. 

• Production of chlorine from salt (sodium chloride). 


ME 21/11/12 V7

Aluminum is produced from electrolysis of alumina (aluminum oxide) at Hillside Aluminum in 

Richards Bay. South Africa is ranked eighth in the world for the production of aluminum. 

Try This Out! 

Figure 3: Electrolysis Set Up 


Electrolysis can produce a chemical change in ionic substances. 

Ionic substances are broken down into simpler substances using an 

electrical current. During electrolysis, the positive ions move towards 

the negative electrode and the negative ions move towards 

the positive electrode. 

You will need a clear cup or beaker, clean water (distilled water is better), 

table salt, a 9-volt battery, thin insulated electric wire and two electrodes. 

The electrodes can be two copper strips or two HB pencils that are sharpened 

at both ends. 

Make up a solution of salt in water by dissolving 10 grams in 

90ml of water for every approximate 100 ml solution you need. 

For example, dissolving 50 grams of salt in 450 ml water will 

yield approximately 500 ml of solution. Connect one end of each 

electrode to one pole of the battery with the electric wire. 

Place the other ends of the two electrodes into the salt solution. 

If done correctly, you should notice the gas bubbles appearing 

at each electrode. 


Jumping Disc 

The Exhibit 

The exhibit allows visitors to charge a 

capacitor and then release its charge to a coil. 

This causes the transfer of the charge to a disc. 

This results in the disc jumping up a tube. 


A capacitor consists of two conductors separated 

by a non-conductive region or an electrical 

insulator also known as a dielectric. Within this 

non-conductive area, an electrical field is 

developed and stored using an external source. 

It is able to store electrical energy similar to a 

battery, but when discharged, it released all of the 

electrical energy stored. A capacitor is assumed to 

be independent and isolated, with no net electric 

charge and no influence from any external 

electric field. 

History 

Figure 1: Jumping Disc 

Figure 2: A Capacitor Circuit 

The Leyden jar is a device that “stores” static electricity between two electrodes 

on the inside and outside of a glass jar. It is accredited as the first actual 

capacitor. It was developed independently by German scientist, Edward Georg von Kleist, 

in 1745 and in 1746 by Pieter van Musschenbroek, a Dutch professor from the University of Leyden. 

Both Benjamin Franklin and Michael Faraday conducted several experiments on earlier capacitors. 

As a result of Faraday’s achievements, the unit of measurement for capacitors, or capacitance, 

become known as the farad (F). 


Commercial capacitors are available in many different forms Figure and strengths 2: A Capacitive Screen 

and are common in electronic and electrical systems. Their capacitance ranges 

from very low (micro farad) to super capacitors (kilo farad). They are commonly 

used to maintain power while batteries are being charged. 

Amplifiers in car audio systems get energy on demand from capacitors. Camera flashes use 

capacitors to hold a high voltage. Capacitors are also used to supply huge pulses of current for 

many pulsed power applications. They are also used in power supplies to smooth the power output 

by blocking direct current and at the same time, allowing alternating current to flow through. 


ME 21/11/12 V7


Capacitors are used in some 

touch screen monitors using 

capacitive sensing technology. 

In capacitive sensing, the touch 

panel is an insulator (usually 

glass) and covering the glass is a thin covering of a 

conductor i.e. indium tin oxide. In this system, a layer of 

electric charge is stored on the layer of the monitor. 

When the monitor is touched, some of the charge is 

transferred to the user, decreasing the amount of charge on 

the capacitor layer. This decrease is then captured and 

analyzed by the touch screen software. 

In Apple Iphone’s touch screen, it is unique in the sense 

that every position on the screen has its own capacitor. 

This means that every position can send its own signal to 

the touch screen software. This is the reason you can use 

more than one finger to touch more than one place 

at a time i.e. pinching to zoom. 

Try This Out! 

You can make your own capacitor from 

three disposable plastic cups and some 

aluminium foil. 

Figure 3: A Capacitive Screen 

1. Cut out the bottom of the one cup with a craft knife. 

2. Make a 1cm mark around the cup from the top. Cut the cup down the side. Cut off the 1cm edge 

at the top of the cup. Open it up. Use this as a template to cut your aluminium foil. 

3. Fold a sheet of aluminiumfoil (about 30cm X 40cm) in two. 

The folded sheet must be bigger than your template. 

4. Mark out the template on the folded aluminium sheet. 

Mark an extra 1cm at both ends and an extra 2cm at the bottom. 

5. Cut out the aluminium foil with a scissors. You should have 2 curved pieces of foil. 

6. Wrap each piece of foil around the outside of each cup from 1cm below the top of the cups 

(see figure). Secure the foil to the cup with some cello tape. 

7. You should still have some foil protruding below 

the cups. Make some cuts into this piece and then fold it under the cup. Secure with cello tape. 

8. Cut a 2cm X 10cm strip of aluminium foil and attach to the foil on the outside of one of the cups. 

9. Put the cup with the strip into the other cup. 

To see how your capacitor stores charge 

do the following: 

1. Rub a PVC pipe with a tissue many times to charge the rod. 

2. Touch the aluminum strip, at the top of your capacitor, with the rod. 

3. Hold the outside of your capacitor in your one hand. 

4. Make a line of about 5 friends holding hands by 

starting with your free hand. 

5. Let the last person close a circle by touching the aluminum strip 

sticking out of your capacitor. What did you feel? 

Figure 3: A Capacitor Circuit 


When a current flows, 

things are magnetized 

Figure 1: When a current flows, 


Figure 2. Components of EM wave 

The Exhibit 

The generator handle is turned to produce an 

electric current in the cable. A magnetic effect 

is observed in the end of the cable by it attracting 

metal filings and washers. 


Electricity and magnetism were originally thought 

to be separate forces. One of the major 

accomplishments of 19th century physics was the 

discovery of electromagnetism by the works of 

Faraday, Maxwell, Heaviside and Hertz. The electromagnetic force is one of four fundamental particle 

interactions in physics. Things like power generation and transmission, industrial 

electromagnets and computers are all based on the interaction between electricity 

and magnetism. 

Forces such as “pulling” and “pushing” come from the intermolecular forces between molecules 

in our bodies and those in the objects. Chemical reactions can occur because of the interactions 

between electron orbital of the interacting molecules. All of these are electromagnetic in nature. 

Not only that, the electric and magnetic fields are also components of visible light and other forms 

of radiation like radio waves, gamma rays and microwaves, collectively known as electromagnetic 

radiations. This is because electric and magnetic field are aligned perpendicular to each other 

when they traverse through space. 

History 

In 1820,Hans Christian Ørsted notices the compass needed being 

deflected from the magnetic north when electrical current from a battery 

nearby was turned on and off, which implied a direct relationship between 


ME 21/11/12 V7

electricity and magnetism. Only a week after the discovery and announcement by Hans Christian 

Ørsted, Ampere published a paper on this phenomoen, he also demonstrated the magnetic 

properties of wires with current in a parallel circuit. This laid the foundation for electrodynamics. 

It was later; James Clerk Maxwell formally formulated the classical theory of electromagnetism, 

unifying the two forces together. The discovery of electromagnetism allowed the development and 

advances in electronic such as the telegraph and telephone. 


Electromagnets are widely used in motors, generators, relays, loudspeakers, 

hard disks and scientific equipment. They are also used to pick up and move heavy 

objects such as scrap iron. MAGLEV trains are suspended by electromagnets. 

By controlling the amount of current that flows through the wires, the strength of the magnetic 

field can be altered accordingly. The magnetic field can also be turn on and off when required. 


When a current flows through a conductor 

such as a copper wire, it creates a 

magnetic field around the conductor 

perpendicular to the flow of current. 

If the conducting wire is wound into a coil, 

the magnetic field is strengthened. 

A much stronger magnetic field can be generated by wrapping the 

coil around ferromagnetic material such as soft iron. The core 

increases the strength of the magnetic field by thousands of times. 

The coil is called a solenoid. The resulting magnet is 

an electromagnet. 

Try This Out! 

Make your own electromagnet. 

You will need one 15cm long iron nail, 3m of 22 gauge insulated 

copper wire, one torch battery (D) and a wire stripper. 

Figure 3: Magnetic field 

around conductor 

Figure 4: Magnetic field 

in a solenoid. 

1. Remove some of the insulation from the end of the wire. 

2. Wrap the wire neatly around the nail, ensuring that there 

is enough wire left at the ends to attach to the 1,5V battery. The wire must only be wrapped in 

one direction. The more wire you wrap the stronger your electromagnet. 

3. Securely attach each stripped end of the wire to one terminal of the battery. 

Pick up a paper clip with your electromagnet. Disconnect one end of the wire from 

the battery and notice what happens to the paper clip. 

Pick up a paper clip with your electromagnet. Disconnect one end of the wire from 

the battery and notice what happens to the paper clip. 

Figure 3: Magnetic 

field in a solenoid. 


The Motor Effect 

Figure 1: The Motor Effect 

Figure 2: The principle behind the motor 

Figure 3: Using a current 

to make a magnet rotate 

Figure 4: World’s smallest electromagnetic 

motor 

The Exhibit 

The principle behind the working of the motor 

is shown in three exhibits. In “The motor effect” and “The 

principle behind the motor” exhibits, a magnet is brought close to 

a current carrying coil to make the coil spin. The same principle 

is shown in “Using a current to make a magnet rotate”, except that 

successive circuits are used to rotate a magnet. 


The world’s smallest electric motor has been built by 

Jos d’Haens, a retired electronics engineer. It has a diameter 

of only 1.3mm, a length of 0.7mm and weighs 3mg. 

It operates on a voltage of 0.220V, has an operating 

current of 18mA and speed range of between 500 – 10,000rpm. 

It is a 3-phase brushless DC motor whose rotor is a small magnet, 

ground to the right dimensions, with a hole for the shaft. 

History 

After Electromagnetism was discovered, 

Michael Faraday was the first to demonstrate 

the conversion of electrical energy to mechanical 

energy by the means of a homopolar motor in 1821. 

Ten years later, Joseph Henry built the earliest ancestor of 

modern DC motor, which used the principle of electromagnetism 

for motion. In 1832, British scientist William Sturgeon built the 

first commutator type DC motor capable of powering machinery. 

Due to the lack of proper power distribution systems, and high 

cost of primary batteries, DC motors were not very successful in 

the early days. However, in 1873, Zénobe Gramme connected two 

electrical dynamos together, producing the Gramme machine, 

which was the first successful motor in the industry. In 1886, 

the first practical DC motor was invented by Frank Sprague, 

which coupled with the developing electrical distribution system 

were a great success. The system powered electrical elevator, 

control system and subway cars. Two years later, 

Nickolas Tesla patented the first practical AC motor in 1888. 


Electric motors are used for applications such as 

fans, blowers, pumps, machine tools, household 

appliances and amongst others computer disc drives. 

The smallest motors are found in electric wristwatches and 

the largest in ship propulsion. 


ME 21/11/12 V7

Motors have revolutionized industry. Almost every machine can be equipped with its own motor, 

providing ease of control at the point of use. By converting electrical energy into mechanical 

energy, they are able to reduce the amount of manual work, and improve efficiency. 


An electric current running 

through magnetic field will 

experience a force that is at 

a right angle to the current. 

If the wire is bent into a loop, 

the opposite sides of the loop will experience forces that 

are opposite to each other. The loops of wire experience a 

difference in force, and produce a torque, 

thereby causing the loop to turn. A mechanical force 

is produced that is able to do useful work. Electrical 

energy has been converted into mechanical energy. 

Fleming’s left-hand rule may be applied to determine the 

direction of the force (motion) with reference to the magnetic 

field and current. 

Try This Out! 

Build an electric motor. You will need: 

1. Three ring shaped magnets (or a neodymium magnet) 

2. Thin insulated electric wire (about 120cm) 

3. One D-size size battery 

4. Two large paper clips 

5. Insulation tape 

6. Wire cutter or stripper 

Figure 5: 

Electric Motor 

Diagram 

Figure 6: 

Fleming’s Left 

Hand Rule 

Instructions: 

Figure 7: The motor coil 

1. Cut the wire into three pieces, one 80cm and the other two 60cm long. 

2. Strip about 2cm of insulation from each end of the wires. 

3. Use the large wire to make a coil. Wrap it around two fingers 

starting about 5cm from the end. 

4. Wrap the long end of the coil around the opposite side 

of the coil and the other end around its side of the coil (see figure). 

5. Make two coil holders with the paper clips. Bend the paperclip; Figure 8: 

use one half as the base and make a loop in the other half. 

The complete motor 

6. Attach the base of each paperclip to one of the short 

electrical wires. 

7. Tape one paper clip base to a table and pile the three magnets 

next to it. Tape the other paper clip on the opposite end. 

8. Put the ends of the coil through the loops of the paperclips above the magnets. 

It should turn freely about 1cm above the magnet pile. 

9. Connect the other ends of the loose wires to the poles of the battery. 

10. Give the coil a gentle spin and see what happens! 


Electromagnetic 

Induction and Transformers 

The Exhibit 

The exhibit is a combination of transformation of electricity and capacitance. 

AC current is stepped down, then converted to DC and then stepped up again. 


Without transformers, we would not be able to 

have the type of electric power distribution 

network (grid) we see today. Electricity generated 

from power plants are converted to high voltage, 

low ampere currents. This reduces power loss 

through transmission over long distances. 

This current needs to be stepped down to a lower 

voltage (220v) before it can be used in a household. 

A series of transformers are used along the 

transmission route to step down the voltage and 

deliver usable electricity to household use. 

AC power is used for transmission because it can be 

stepped up or down by transformers easily. 

DC power is used for transmission of power across 

vast distances (under the ocean). 


Figure 1: Electromagnetic Induction and 

Transformers 

History 

Figure 2: High voltage transmission 

Michael Faraday created the first 

closed-core transformer in 1831 during experiments with electromagnetism. 

The induction coil invented by Rev. Nicholas Callan in Ireland in 1836 was the first 

transformer to see wide practical use. By the 1870s, it was found that power transformers could 

easily change the voltage of the current in AC power. Whereas in order to change the voltage in DC 

power, large spinning rotary converter was needed, this proved to be expensive, inefficient, 

and required maintenance. In the 1880s more efficient practical transformers were designed, 

which helped AC power distribution win over DC power distribution. After the 1891, the invention 

of the Tesla coil by Nicola Tesla for generation of very high voltages at high frequency leads to 

the development of audio frequency transformers. This made the development of the telephone 

and radio possible. 


Transformers come in a range of sizes from the thumbnail size, found inside stage microphones, 

to huge units that weigh hundreds of kilos for connecting portions to power grids. Almost all 

electronic devices that have to work off the household voltage will have a transformer. 

This is because the current coming into the household is high voltage and electronic equipment 

like PC boards requires low voltage supply. A cell phone charger is basically a transformer. 


ME 21/11/12 V7


Transformers are based on the principles that an electric current can 

produce a magnetic field (electromagnetism) and that a changing 

magnetic field (flux) in the coil produces a voltage across the ends of 

the coil (induction). Transformers have two coils: a primary and 

a secondary coil. If the current in the primary coil is changed (i.e. AC), 

it creates a changing magnetic field, which creates a current in the secondary coil. 

The voltages (V) or number of turns (N) required is 

be calculated from Faraday’s law, which gives: 

Try This Out! 

Build your own transformer. You will need: 

Figure 3: A transformer 

• 4 pieces of flat bar steel (2 long & 2 short) 

with holes on ends for bolts 

• 4 bolts with nuts & washers to fit holes in flat bar 

• 28 gauge “magnet” wire (has thin enamel coating) 

• A low voltage AC transformer (e.g. 12V AC) with switch 

• Insulation tape 

• Multi test meter to measure AC voltage. 

Instructions: 

1. Wrap the two long bars with a thin layer of insulation tape. 

2. Wrap several hundred turns of magnet wire around these bars keeping the ends exposed. 

Leaves the ends of the wire exposed for connecting. The number of windings on each bar 

will be unequal if you want a step up or step down transformer. 

3. Join the bars together in a rectangle with the bolts (see illustration). 

Figure 2: Transformer illustration 

4. To see your transformer working, connect one coil to a low voltage AC transformer and 

connect this transformer to the wall socket (220V). 

Do not connect your transformer directly into the wall socket! 

Switch on the current to your set up and measure the output voltage of your transformer 

from the secondary coil using an AC voltmeter. 


The Generator 

Figure 1: The Generator 

Figure 2: The magnet within the coil 

Figure 3: The coil within the magnet 

Figure 3: Exhibit – The coil 

within the magnet 

The Exhibit 

The principle of the generator is presented in 

four exhibits. In “The Generator,” visitors turn a 

magnet near a coil and observe the current 

produced in the coil on a galvanometer. In the 

“Magnet within a coil” exhibit, the magnet is turned 

inside a coil and the resulting current is seen by 

means of a lamp glowing. The reverse is done with 

the “Coil within the magnet” exhibit, where the coil 

is turned and the magnet is stationary. In the 

“Spinning lights” exhibit a wheel that has coils 

attached to it is spun. As the coils move pass 

the magnets small LED lights glow. 


Before CDs and magnetic tapes, audio 

recordings were captured on patterns of 

grooves cut into a vinyl record. A needle on the 

phonograph cartridge is able to read these 

grooves. The movement and vibrations from the 

needle cause a magnet to move up and down pass 

a coil of wire. A corresponding electrical signal is 

generated by this moving magnet, which is then 

transmitted to the amplifier and speakers as sound 

History 

The first electricity generators 

were based on electrostatic 

principles. They produced high 

voltages and low currents which were not suitable 

for commercial generation of electricity. 

Soon after the discovery of the relationship that exist 

between electricity and magnetism, Michael Faraday 

built the first the electric motor in 1821 using the 

principle of electromagnetic induction. In 1832, 

Hippolyte Pixii built an early form of alternating 

current electrical generator, based on the principle 

of magnetic induction discovered by Michael 

Faraday. From these inventions, electric dynamo 

were eventually built and used for power generation. 


Electric generators are used to convert 

mechanical energy into electrical energy. 

This mechanical energy may be from a water wheel, 


ME 21/11/12 V7

Figure 4: Spinning Lights 

Figure 5: A phonograph cartridge and 

vinyl record 

Figure 6: Working of a dynamo 

Figure 7: A simple generator 

steam, internal combustion engine or other sources. 

Majority of the developing country uses coal based power 

plants, which is a form of combustion engine. 

Environmental concerns of using fossil fuels have led 

to an increasing use of wind, solar and hydropower. 


Electromagnetic induction is used 

in generators to produce electricity. 

A magnet is made to rotate inside a 

coil. This induces an electric current 

in the coil. The current generated can then be used for 

various appliances. The rotation of the magnets is 

generated from devices driven by mechanical force such 

as the turning of the turbine in a wind powered generator. 

Try This Out! 

Build your own simple generator. 

You will need: 

1. Four 1x2x5cm ceramic magnets (or smaller 

neodymium magnets). 

2. 60m magnet wire 30gauge (0.3mm coated copper 

wire). Can use more to make the generator 

stronger. 

3. A miniature globe, 1.5V 25mA incandescent or an light 

emitting diode (LED) 

4. Cardboard strip, 8cm x 30.4cm. 

5. A large nail, 8cm or more in length. 

6. Knife or sandpaper, tape and hand drill. 

To build the generator: 

1. Make a box from your cardboard strip. Score as shown 

below. Fold on the score lines and tape together. 

2. Make a hole in the center of the wide side of the 

box so that the nail fits right through the box and 

is able to spin freely. 

3. Put the nail through the box and tape or fasten the 

magnets to the nail. Put two on to and two at 

the bottom of the nail. The long side of the magnets 

must be at 90° to the nail. Make sure all poles 

correspond; check by first putting them on top of each 

other. Your magnets must be able to spin freely, 

by turning the nail, without knocking the sides of 

the box. 

4. Wind the wire around the box as shown in the 

figure. Ensure that about 10cm of each end sticks out. 

5. Clean the insulating coating of the ends of the 

wire (about 2cm) and twist each end to the 

terminals of the globe. 

6. A hand drill can be used to spin the nail and magnets 

if care is taken not to injure yourself 


Electric Fleas 

The Exhibit 

The exhibit contains polystyrene pieces (white fleas) in a clear 

Acrylic plastic -box and two white brushes. When the top of the 

box is rubbed with the brush some electrons are transferred 

from the brush to the box causing it to become negatively 

charged. This causes some of the positively charged white fleas 

to attract to the top of the box. This exhibit is an example 

of static electricity. 


All matter is made up of atoms which contain negatively 

charged particles called electrons and positively charged 

particles called protons. In a neutral atom, the positive and 

negative charges are equal. If we remove electrons from the 

material, it becomes positively charged and if we add electrons 

to the material, it becomes negatively charged. Surface charge 

(or electrostatics) is the accumulation of these charges on the 

surface of materials. 

This electricity is called “static” because the electrons tend to 

remain stationery after being moved from one material to the 

other. Oppositely charged materials will attract each other and 

like charged materials will repel each other. In the exhibit, 

the box becomes charged when it is brushed which gives it the 

ability to attract the polystyrene pieces. 

History 

In 600 BC, the Greek mathematician, 

Thales, noticed that amber rubbed with fur 

attracted light objects. At that time people confused 

static electricity with magnetism. 

Figure 3: Charges 

Materials like copper and silver were not able to attract objects no matter how much they were 

rubbed. These were called conductors because they allowed electricity to flow instead of remain 

on the material. 

In 1780, a French physicist, Charles Coulomb, used a device called a torsional balance to 

measure the force between two electrically charged objects. Today, the unit of electrical charge, 

the coulomb, is named in his honour. 


Figure 1: Electric Fleas 

Figure 2: The Atom 

Balanced Atom 

Net Charge Zero 

Carbon atom 

Xerography or electrophotography is a dry ink photocopying technique that 

uses electrostatics. It is used in most photocopying machines and in laser printers. 

Deficiency of 

Electrons 

Net Charge 

Positive 

6 protons 

+ 6 neutrons 

electron 

proton 

neutron 

Excess of 

Electrons 

Net Negative 

Charge 


ME 21/11/12 V7

Surface charge is also used in a factory’s smokestacks. In 

this system, the smoke is negatively charged as it rises up 

the stack, and is then trapped by positively charged collecting 

plates before it can go out of the stack thus reducing the 

amount of pollution emitted from the plant. 


Charles Coulomb studied the 

strength of electric force at two charges. 

He developed an equation which 

explained the amount of force between 

two electrostatic charges: 

f = K c 

q1 x q2 

r 2 

From this equation, the strength of the electrostatic force is depended on the distance between 

two charged particles as well as the quantity of charge on the particle. The further the distance, the 

weaker the charge, and the stronger the charge on the particle, the stronger force there 

will be between the particles. 

Try This Out! 

f = electrostatic force 

K 

c 

= Columb’s Constant 

q = scale of each charge 

r = distance between the two charges 

1. Clean two empty soda cans and remove the pull tops from each of the cans. 

Tie a piece of sewing thread about 150mm in length to one of the pull top lids. 

2. Tie the other end of the thread to a pencil so that the pull top lid hangs about 10cm below 

the pencil. 

3. Stand the two soda cans side-by-side on top of an old CRT 

(cathode ray tube) television or computer monitor so that they 

are spaced about 50mm apart. 

4. Place the pencil horizontally on top of the two cans, so the 

pull-tab is suspended freely. 

Figure 4: Danger Sign 

5. Use two insulated wires of about 60 – 100cm in length with c Figure 5: Electrostatic Bell 

rocodile clips to one end. Tape the bare end of one of the wires 

to the left can to form the ‘ground’ wire. Connect the free end of 

the ‘ground’ wire to an electrical ground, such as a cold water pipe. If an electrical ‘ground’ 

is not available, you can just hold onto the free end, as your body would be a good enough ‘ 

ground’ for this device. 

6. Use sticky tape to tape the remaining wire to the soda can on the right. This wire’s free end will be 

connected to a source of high voltage. 

Pencil 

Sewing thread 

Pull-top lid 

Soda cans 

Connection wires 

Aluminium foil 

CRT Television 

7. Press a 30x50cm piece of aluminium foil onto the face of the TV screen, and hold it in position with 

sticky tape. When the TV screen is switched on, it becomes highly charged with electricity and the foil 

will stick to the screen. Connect the free end of the wire in step ‘7’ to the piece of aluminium foil. 

8. Start the device by turning on the TV. The pull-top lid gets pulled to one can, but when it hits it, it 

gets pulled to the other can, and then repeats! 


Ground 

wire

Luminglas 

Display electrodes 

(inside the dielectric 

layers) 

Dielectric layer 

Front plate glass 

A schematic matrix 

electrode configuration 

an AC PDP 

Magnesium oxide coating 

Rear plate glass 

Dielectric layer 

Address electrode 

Pixel 

Phosphor 

coating in 

Plasma cells 

The Exhibit 

The exhibit is a luminglas that is placed in a 

table. Visitors can watch the neon colored lighting 

display as it moves and also touch the glass to see 

the change that takes place. 


The filaments of light in the luminglas are 

produced by discharging high frequency, 

low power electrostatic electricity into a cavity 

Figure 1: Luminglas 

filled with phosphor coated beads. The cavity also 

contains a mixture of gases such as helium, neon, 

xenon or krypton at low pressure. An electrode is located in the centre of the luminglas. 

Electrostatic discharge in the form of plasma filaments of light is generated from this electrode 

to the outer glass insulator. Energy from the lights excites the phosphorus on the beads and as 

a result, the phosphorous atoms emit fluorescent light. Placing your hands on the glass causes 

the electric field to be altered causing the plasma beam to move from the inner electrode to where 

your hand is! 

History 

Plasma was first identified by Sir William Crooke in 1879. Nikola Tesla discovered 

the luminglas after his experiments with high frequency currents in 1894. 

Tesla’s concept was taken and used almost a century later in 1970 by Bill Parker, 

an undergraduate student at MIT, to design the modern plasma globes. 


The application of plasmas can be seen in many areas in industry 

such as in thermal spray coating, etching in microelectronics, 

metal cutting and welding. The most common application 

is in fluorescent or neon lights. 

Today’s plasma TV is an example of luminglas concept. The display is 

an array of hundreds of thousands of small luminous cells positioned 

between two plates of glass. The picture changes when the color 

changes in each individual cell. 

Figure 2: Composition of 

a Plasma Display 


ME 21/11/12 V7


The luminglas makes use of a state of matter called plasma, 

which is a state of gas, where a certain portion of the gas mixture 

is ionized by an electric or magnetic field. The presence of ions makes 

plasma electrically conductive thus it responds strongly to 

electromagnetic fields. Under the influence of EM fields it may form 

structures such as filaments, beams and double layers. 

Plasma is the most common state of matter in the universe, 

99% of matter is in the state of plasma. Stars like our sun are 

made out of plasma. Lightning is an example of plasma present at the Earth’s surface. 

Plasma may be produced by applying an electric current across a dielectric gas. 

When there is enough current density and ionization takes place, 

an electric arc is formed between the electrodes. 

Try This Out! 

Compare a plasma TV to a cathode 

ray tube (CRT) TV. Switch on both and 

compare the color and contrasts of the pictures 

on each set. Which TV becomes hotter after 

the same time interval? High temperature indicates 

higher power consumption! 

Figure 3: A Discharge Tube 


Spark Plugs 

The Exhibit 

The exhibit consists of an ignition coil and 

a distributor connected to 4 spark plugs. 

Visitors can turn a crank handle that causes 

the dynamo to send a current to the ignition coil. 

This current passes through the distributor and 

creates a spark from the plugs. The plug spark 

in a set firing order to simulate what happens 

in a vehicle’s ignition system. 


The vehicle’s ignition system creates an electric 

spark in the cylinder of the engine which ignites 

the fuel-air mixture in the combustion chamber. 

The spark plug receives high voltage electric 

current from the car battery which “jumps” from 

the positive terminal to the negative terminal 

separated by a gap on the plug. The current is able 

to pass through the gas because the gas is ionized 

due to the high voltage on the terminals. 

As electrons surge across the gap, 

the temperature between the gap increases 

rapidly to about 60 000 K. The intense heat causes 

the ionized gas to expand very quickly, like a mini 

explosion which causes the small ball of fire to 

ignite the rest of the gas fuel mixture in the 

combustion chamber. The ignition coil is the 

component that steps up the 12 volts from the 

battery into the high 20 000 volts charge 


History 


Figure 2: A Spark Plug 

The spark plug was invented in 1860 by Étienne Lenoir. In 1902 Gottlob Honold, 

an engineer from the Bosch corporation invented the first commercially viable 

high-voltage spark plug. This led to the development of the internal 

combustion engine. 

There are three different types of ignition systems that are used on vehicles. 

The Mechanical Ignition System, such as in this exhibit, was used before 1975 

and is entirely mechanical and electrical in nature. The Electronic Ignition 

System uses electronic components to time the spark plug for proper ignition, 

which greatly increase the efficiency and the performance of the spark plug. 

It was incorporated into engines from 1970s onwards. 


ME 21/11/12 V7

Modern automobiles ignitions system are completely controlled by onboard computers, they also 

lack a distributor which is involved in the spark plug ignition timing (done by computer instead). 

For this reason, these newer ignition systems are also called Distributor-less system. Unlike its 

predecessors, this new system contains no moving parts, which greatly improve the reliability 

offers greater control over the older systems. 

Try this Out! 


Look inside the bonnet of a vehicle 

and try to locate the coil, distributor and where 

the spark plugs fit into the engine. Obtain a 

spark plug from a mechanic or a motor spares 

shop and see if you can identify the different 

parts of this plug. Look for the place where 

the spark is produced. 

In order for proper ignition, there needs to be proper timing and 

distribution of the spark in the ignition chamber to light the fuel 

mixture. This is done by the distributor, which routes high voltage 

from the ignition coil to the spark plug in the correct firing order. Try 

Figure 3: The Mechanical Ignition System. 

Figure 4: Spark Plug Cutaway. 


Jacob’s Ladder The Exhibit 

Figure 1: Jacob’s Ladder 

Figure 2: Ionization 


An electric arc is created between two 

electrodes when visitors press the switch. 

The arc moves up the diverging electrodes. 


Gases are poor conductors of electricity due to 

the large distance between the gas particles. 

It becomes a good conductor when it is 

ionized. Thus when an electric field becomes 

very strong, it causes the surrounding gas mixture 

to become separated into positive ions and electrons. 

The electrons and positive ions are farther 

apart than they were in their original molecular or 

atomic structure. Essentially, the electrons have 

been stripped from the molecular structure of the 

non-ionized gas. The importance of this separation/ 

stripping is that the electrons are now free to move 

much more easily than they could before the 

separation. So this ionized gas mixture (plasma) is 

much more conductive than the previous 

non-ionized gas mixture. 

History 

The electric arc was first 

described by Vasily V. Petrov, 

a Russian scientist, in 1802 as 

a “special fluid with electrical properties.” 

Sir Humphry Davy first studied the electric arc in 

1801. In 1808 he demonstrated a large-scale arc to 

the Royal Society. These experiments gave him an 

understanding and allowed him to invent the first 

electric lamp in 1809. Davy connected two wires 

to a battery and attached a charcoal strip between 

the ends of the wires; the charcoal glowed, 

producing light to illuminate the surroundings 

using electricity. 

Electric arcs have wide usages; they can be used as luminous lamps, furnaces, for heating, cutting, 

and welding and as tools for certain types of chemical analyses. 

Arc welders are used for fusing pieces of metals. Plasma torches are used for cutting, 

spraying and gas heating. Electric arcs are often used as lamps because of the amount of light they 

produce. They have been used in radio valves and as a source of ions in nuclear 


ME 21/11/12 V7

Figure 3: An Electric Arc Lamp 


reactors and thermonuclear devices. 

A vehicle’s spark plug produces an arc that is used to 

ignite the fuel 

in the engine. 

High intensity discharge (HID) lamps produce a large 

amount of light in a relatively small area. They produce 

light by means of a heated gas with an electric arc 

as opposed to incandescent lamps that use a heated 

filament. The starting voltage must be higher than the 

operating voltage in order to break down the gas in 

the chamber. This is achieved by means of a capacitor, 

which supplies sufficient high voltage for starting and 

for the lamp to strike every half cycle. 

The spark that is created in the Jacob’s Ladder exhibit ionizes and 

heats the surrounding air. This ionized air is much warmer and rises. 

This causes the next spark to be created higher up the electrodes, 

producing the effect of a climbing arc. The stability of the arc 

diminishes as the distance between the electrodes increases. 

When the arc finally snaps at the top, the voltage at the bottom of the electrodes increases again 

and a new arc starts. 

The noises coming from the chamber are caused by the forceful stripping of electrons from 

the air molecules. The pitch of the sound changes as the arc climbs higher. 

Try This Out! 

Make an electric arc. You will need: 

1. A stainless steel pan 

2. A woolen sock 

3. Rubber gloves 

4. A stainless steel fork 

Procedure: 

1. Wear rubber gloves to avoid getting shocked. Spread the woolen sock out on a flat clean 

wooden, plastic or glass table. Do not use a metal table. 

2. Put the bottom of the pan on the sock and rub it back and forth firmly and rapidly for 

about 30 seconds. 

3. Darken the room as much as you can. Bring the fork slowly towards the rim of the pan. 

When it gets close to the rim you will see an arc of electricity between the fork and the pan. 


Is it a Conductor? 

Teaching Guide and References 

Exhibit Objectives 

The exhibits aim to: 

1. Identify which types of material are conductors of electricity. 

2. Identify which materials are non-conductors (insulators) of electricity. 

3. Show that only conductors can be placed in an electric circuit. 

4. Show that current only fl ows through conductors. 

School Curriculum Links 

Grade Learning Area / Subject Topic Section / Example 

1,2,3 Life Skills Safety in and Electricity, switches, wires. 

around he t ehous 

4,5,6 Life Orientation Safety in and Electricity, switches, wires, 

around the house isolators. 

Natural ience Sc Electricity Circuits 

Technology Electricity Circuits 

7,8,9 Technology Electricity Circuits nd aawing 

dr ircuits of c 

Natural Science Electricity Circuits and drawing of circuits 

10,11,12 Physical Science Electricity Drawing, building and 

calculating ircuits. c 

Questions 

Matter nd a 

Conductors, emiconductors s 

Material and nsulators. i 

Electrochemistry Electrochemical ells cnd 

electrolytic ells. c 

a 

Industrial hemistry c Batteries nd aor-Alkali 

Chl ells. c 

Electrical Technology Electricity & Electronics Drawing, building and 


Mechanical echnology T Electricity Drawing, lding bui nd a 

Engineering Graphics & 

Design 

Electricity & Electronics 


Drawing circuit diagrams. 

Grade 1,2,3: 

1. Should you use an electric kettle with exposed wires in order to boil water? 

2. If the electricity is on, will you shock if you touch wires that are covered in plastic or tape? 

Grade 4,5,6: 

3. If an electric circuit is constructed by connecting a battery, a light bulb, electric wires and a 

glass tube, will the light bulb come on? 

4. What are some examples of conductors and insulators of electricity? 


ME 21/11/12 V7

Grade 7 – 9: 

5. Is a carbon rod a good conductor of electricity? Where is it used? 

6. Although silver and gold are the best conductors of electricity, 

why is copper wire commonly used? 

Grade 10,11,12: 

7. Why are metals good conductors of electricity? 

8. What are superconductors and semiconductors? 

Interesting Websites Links and References 

1. NDT Resource Center, Conductors and Insulators, Available at: < http://www.ndt-ed.org/ 

EducationResources/HighSchool/Electricity/conductorsinsulators.htm> [ 

Accessed 07 May 2011]. 

2. Wikipedia, Electrical conductor, 2011, (Updated 2 May 2011) Available at: < http:// 

en.wikipedia.org/wiki/Electrical_conductor> [Accessed 07 May 2011]. 

3. Kids Ed Websites, 2011, Blobz Guide to Electric Circuits, Available at: [Accessed 7 May 2011]. 

4. BBC KS2 Bitesize, Electric charge, 2011, Available at: [ 


5. BBC KS2 Bitesize, Electrical coductors - Quiz, 2011, Available at: < http://www.bbc.co.uk/ 

apps/ifl/schools/ks2bitesize/science/quizengine?quiz=circuitsandconductors&templateStyl 

e=science> [Accessed 7 May 2011]. 

6. NeoK12, 2011, Conductors & Insulators, Available at: [Accessed 10 May 2011]. 

Figure References 

1. Sci-Bono Exhibit. 


3. BBC KS2 Bitesize, Electric charge, 2011, Available at: [ 


4. Daily Science Page, Electricity – Grade 5, Available at: [Accessed 7 May 2011]. 

5. Dirtmeister, Science Lab on Circuits, Available at: [Accessed 10 May 2011]. 

Answers to Question 

1. No. It is unsafe to touch any open wires when the electricity is switched on. 

You might shock using the kettle in the process. 

2. No. The wire will be insulated and you will not shock. 

3. No the light bulb will not come on, because the glass tube is an insulator. 

4. Conductors: Silver, copper, gold, graphite, salt solution. 

Insulators: Glass, rubber, plastic, oil, dry paper. 

5. Yes. It is used in the construction of batteries. 

6. Copper is commonly used because it has a high conductivity and is inexpensive. 

7. Metals are good conductors because they have free electrons. 

8. See under “More to Consider.” 


Completing the Circuit: 



The exhibit aims to: 

1. Demonstrate that current will only fl ow if a circuit is closed. 



1,2,3 Life Skills Safety in and Electricity, switches, wires 


4,5,6 Life Orientation Safety in and Electricity, switches, wires. 

around he t e hous 



7,8,9 Technology Electricity Circuits and drawing of circuits 



calculating ircuits c 

Electrical Technology Electricity & Drawing, building and 

Electronics calculating ircuits c 

Mechanical echnology T Electricity Drawing, lding bui nd a 

Engineering Graphics Electricity & 


Drawing circuit diagrams 

& esign D 

Electronics 

Questions 

Grade 1,2,3: 

1. Name some household appliances that work with electricity. 

2. How do you get electricity to these appliances? 

Grade 4,5,6: 

3. Explain how you would connect a battery to a light bulb to make the bulb shine. 

4. Draw a diagram of the connection that you have made. 

Grade 7,8,9: 

5. Draw a circuit diagram of an open and a closed circuit. 

6. What things could be wrong if the light bulb in a complete circuit does not light up? 


ME 21/11/12 V7

Grade 10,11,12: 

7. How can you modify the circuit or its components in the exhibit to make the bulb 

burn brighter? 

8. How can you modify the circuit or its components in the exhibit to make the bulb 

burn less bright? 

References and Interesting Websites Links 

1. Sidney Soclof, 2008-2011, How Circuits Work, Available at: [Accessed 29 April 2011]. 

2. Wikipedia, Electric Circuit, (updated 14 April 2011) Available at: [Accessed 30 April 2011]. 

3. Edkins Family Interactive Web Page, 2010, Introduction to Electricity - Voltage, Current, 

Resistance, Available at: 

[Accessed 30 April 2011]. 

4. Wikipedia, Alessandro Volta, (Updated 29 April 2011) Available at: [Accessed 30 April 2011]. 

5. Child Media, Electric Circuits: An interactive E-learning website, Available at [Accessed 30 April 2011]. 

6. Elizabeth Sluder and Daniel Friedman, 2011, Electrical Circuit Basics for Homeowners, 

Available from: 

[Accessed 2 May 2011]. 


1. Sci-Bono exhibit. 



4. All About Circuits, Conductor, Insulators, and Electron Flow, Available at: 


5. All About Circuits, Conductor, Insulators, and Electron Flow, Available at: 



1. A stove, a microwave, a refrigerator. a television set, etc. 

2. You connect them to the electrical socket and switch it on. 

3. Connect one pole of the battery to one point of the bulb and the other pole to the other point 

of the bulb. Some bulbs have the two points at the bottom of the bulb. Others have one 

point at the bottom and the other on the side of the bulb. 

4. 

http://iss.cet.edu/electricity/pages/a12.xml http://electrosparx.blogspot.com/2011/04/ 

electrical-circuits-voltmeters-and.html 

5. 

Supply 

Closed Switch 

6. The bulbs filament could be broken. The electrical source could be depleted. There could be 

a break somewhere in the circuit. There could be a short circuit. 

7. You can add an extra battery or higher voltage battery. 

8. You can use a lower voltage battery or add a resistor or another load to the circuit. 

I 


I 

Open Switch 

(a) (b)

Puzzle Circuit 




1. Demonstrate a parallel electric circuit. 

2. Demonstrate the splitting of electric current. 

3. Show that current is conserved in a circuit. 

4. Show the difference between a series and a parallel connection. 

5. Demonstrate the functioning of an ammeter. 

6. Enable learners to trace the fl ow of current. 



1,2,3 Life Skills Safety in and Electricity, switches, wires. 


4,5,6 Life Orientation Safety in and Electricity, switches, wires. 

around the house 








Questions 

Electrical Matter nd a 

Figure 6: Light Bulb & Battery 

Drawing, lding bui nd a 

Technology Material calculating ircuits. c 

Mechanical Electricity Drawing, lding bui nd a 

Technology calculating ircuits. c 

Mechanical Technology Electricity & Drawing circuit diagrams. 

Graphics esign & D Electronics 

Grade 1,2,3: 

1. If the electricity is switched off, will the water in an electric kettle boil? 

2. If the electricity is on, will you shock if you touch open wires? 

Grade 4,5,6: 

3. Given a battery and a light bulb, show how you would connect these two devices 

together with wire so as to energize the light bulb: 


ME 21/11/12 V7

4. How will you connect these two light bulbs in order 

for it to burn very bright? 

Grade 7 – 9: 

5. Are the lights in your house connected in series or parallel? 

6. Are the Christmas lights on a tree connected in series or parallel? 

Figure 7: Two Light Bulbs & Battery 

Grade 10,11,12: 

7. When will a circuit be classified as a potential energy divider and give an example? 

8. When will a circuit be classified as a current divider and give an example? 


1) Sidney Soclof, 2008-2011, How Circuits Work, Available at: [Accessed 29 April 2011]. 

2) Wikipedia, Electric Circuit, (updated 14 April 2011) Available at: [Accessed 30 April 2011]. 

3) Edkins Family Interactive Web Page, 2010, Introduction to Electricity - Voltage, Current, 

Resistance,Available at: 


4) Wikipedia, Alessandro Volta, (Updated 29 April 2011) Available at: [Accessed 30 April 2011]. 

5) Child Media, Electric Circuits: An interactive E-learning website, Available at [Accessed 30 April 2011]. 



2. http://www.electrical-design-tutor.com/seriesparallel.html. 

3. http://www.electrical-design-tutor.com/seriesparallel.html. 

4. http://www.ehow.com/facts_6885169_definition-pc-board.html. 

5. http://www.thereminworld.com/silicon_chip_theremin_modifications.html. 

6. MPower diagram. 

7. MPower diagram. 


1. No. Electricity is a form of energy. 

2. Yes. Unsafe to touch any open wires when the electricity is switch on. 

3. Thisisthesimplestoption, but nottheonlyone. 4. 

5. Parallel. 

6. Series. 

7. A series circuit is a potential energy divider. Christmas light. 

The voltage for each light is very low. Current remain constant 

8. Parallel circuit is a current divider. The electricity in your house is connected in parallel. 

The voltage remains the same – 240 V. 


Electricity Travels Through 

My Body 




1. Show that people are conductors of electricity. 

2. Show that electricity can be dangerous. 



1,2,3 Life Skills Safety in and around Electricity, switches, wires. 

the ehous 

4,5,6 Life Orientation Safety in and around Electricity, switches, wires. 

the e hous 

Lightning 

Natural ience Sc Electricity Current ow 

Conductors 

fl 

Technology Electricity Current ow fl 

7,8,9 Technology Electricity Current ow fl 

Natural ience Sc Electricity Current ow 

Ionic olution s 

fl 

10,11,12 Physical Science Electricity Current fl ow 

Ionic olutions s 

Life iences Sc 

Human Body Nervous ystems 

Electrolytes 

Questions 

Grade 1,2,3: 

1. Will you shock if you touch someone else who is having an electric shock? 

2. What could happen if electricity travels through you? 

Grade 4,5,6: 

3. Do you have to be touching the ground directly to conduct electricity? 

4. Is it easier to get an electric shock if you touch the source with wet hands or with dry hands? 

Grade 7,8,9: 

5. Why is the human body a conductor of electricity? 

6. Does oil conduct electricity? Why? 

Grade 10,11,12: 

7. Which is a better conductor of electricity, a 10% salt solution or a 10% acetic acid solution? 

8. List some common electrolytes found in the human body? 


ME 21/11/12 V7


1. All About Circuits, 2011, Ohm’s Law (again!), Available at: [Accessed 19 August 2011]. 

2. Nobelprize.org, 2011, The electrocardiogram – looking at the heart of electricity, 

Available at: 

[Accessed 20 August 2011]. 

3. Wikipedia, 2011, Luigi Galvani, (Updated 20 August 2011) Available at: [Accessed 20 August 2011]. 

4. Sha Buckines, Scales That Measure Body Fat, (Updated 03 June 2010) 

Available at: [Accessed 20 August 2011]. 

5. Nobelprize.org, 2011, The electrocardiogram – looking at the heart of electricity, 

Available at: 




2. Sha Buckines, Scales That Measure Body Fat, (Updated 03 June 2010) Available at: 


3. Kerry Redshaw, Picture Gallery: Nikola Tesla (13 of 16), Available at: [Accessed 20 August 2011]. 

4. Nobelprize.org, 2011, The electrocardiogram – looking at the heart of electricity, Available at: 

 


Answers to Questions 

1. Yes. Electricity can travel through the other person and shock you. 

2. You could get shocked. 

3. No. You could touch something else that is touching the ground. 

4. Wet hands. They conduct electricity better than dry hands. 

5. Because the body contains 70% water and many dissolved electrolytes. 

6. No. There are no ions in the oil. 

7. 10% salt. It has more ions in solution. Acetic acid does not dissociate completely. 

8. Sodium, potassium, magnesium, calcium, chloride. 


Feeling Electricity 




1. Show that electricity can move through the human body. 

2. Show that electricity can be felt. 

3. Show that electricity is dangerous. 




the e hous 


the e hous 

Natural ience Sc Electricity Current ow fl 

Technology Electricity Current ow fl 

7,8,9 Technology Electricity Current ow fl 

Natural ience Sc Electricity Current ow fl 


10,11,12 Physical Science Electricity Current fl ow 

Life iences Sc 


Questions 

Grade 1,2,3: 

1. Why do you not get shocked by a cell phone battery? 

2. Should you switch on an electrical appliance while you hands are wet? 

Grade 4,5,6: 

3. Why must electric wire always be insulated? 

4. What does electrocution mean? 

Grade 7,8,9: 

5. What is “ground” or “earth” in electricity? 

6. Will you shock if you are hanging from one overhead live electric cable and your feet are not 

touching the ground? 

Grade 10,11,12: 

7. How is shocking able to kill a person? 

8. Does the human skin have an electrical resistance? 


ME 21/11/12 V7

Questions 

Grade 7,8,9: 

5. What is electrical resistance? 

6. Which has a higher resistance, a short or a long wire? 

Grade 10,11,12: 

7. What metal is commonly used in heating systems? 

8. Why do electrical resistors heat up when a current flows through them? 


1. Wikipedia, 2011, Electric Shock, (Updated 12 August 2011), Available at: 


2. Julia Layton, 2011, How does the body make electricity -- and how does it use it? 


3. Harold Fisher, 2011, What is Electricity, Available at: [Accessed 16 August 2011]. 

4. Darius Rejali, February 1999, Electric Torture: A Global History of a Torture Technology, 




2. Harold Fisher, 2011, What is Electricity, Available at: [Accessed 16 August 2011]. 

3. Julia Layton, 2011, How does the body make electricity -- and how does it use it? Available 

at: [Accessed 16 August 2011] 


1. Because the current and voltage are low. 

2. No. The water on your hands could get into the electrical contacts in the switch and 

the electricity could travel through this to your body. 

3. The insulations protect us from electric shocks. 

4. Death by electricity. 

5. It is a connection to the ground so that electricity can be made to flow into the ground. 

6. No. As long as you are not grounded or closing the circuit you will not shock. 

7. Shocking can cause cardiac arrest. 

8. Yes all electrical conductors have some resistance. 


Bright Lights 




1. Simulate the workings of vehicle’s headlights. 

2. Give an example of where lenses are used. 



1,2,3 Life Skills Road fety Sa 

Illumination 

4,5,6 Life Orientation Road Safety Illumination 



7,8,9 Technology Electricity Circuits 


10,11,12 Physical Science Electricity Drawing & building circuits 

Optics Lenses 

Light Refl ection 

Electrical Technology Electricity &Electronics Drawing & building circuits 

Mechanical echnology T Electricity Circuits 

Engineering Graphics & Electricity & Electronics Drawing circuit diagrams 

Questions 

Grade 1,2,3: 

1. What happens to your vision when a bright light shines into your eyes? 

2. When should a vehicle’s headlights be on? 

Grade 4,5,6: 

3. Should you switch on a vehicle’s bright lights when there is an oncoming vehicle? 

4. How many switch positions are there for a car’s headlights? 

Grade 7,8,9: 

5. Which 12V light bulb will shine brighter one rated 20W or 100W? 

6. On what part of the road are a vehicle’s bright and dim lights aimed? 

Grade 10,11,12: 

7. Where is the refl ector and the lens on a vehicle’s headlamp? 

8. Most of the latest model vehicles are using LED headlamps. 

What is an LED lamp and what are its advantages? 


ME 21/11/12 V7

Bright Lights: 


1. Wikipedia, 2011, Automotive Lighting, (Updated 25 April 2011) Available at: [Accessed 30 April 2011]. 

2. Wikipedia, 2011, Headlamp, (Updated 8 May 2011) Available at: [Accessed 15 May 2011]. 

3. Carjunky.com, 7 May 2006, Car Headlights, Available at: [Accessed 16 May 2011]. 

4. Ed Grabianowski, How Adaptive headlights Work, Available at: [Accessed 25 April 2011]. 


1. Sci-bono exhibit. 



4. Mike Allen, 2011, How Your Headlights Work - Quartz Iodine H13 HID LED Headlights - 

Popular Mechanics, Available at: [Accessed 20 September 2011]. 





1. It will cloud your view and the lights will be very bright for your eyes. 

2. At night or when it is not clear to see in from of you. 

3. No. It is dangerous because you cloud the view of the oncoming driver. 

4. Most cars of latest models have three headlight positions – dim, normal and bright. 

5. The 12V, 100W lamp. The Wattage shows the power rating. 

6. Bright lights are aimed straight ahead and are suitable for use only if there are no other 

cars on the road because the glare can cloud the sight of other drivers.Dims are aimed 

at the road in front of the vehicle. 

7. The reflector is the parabolic back part and the lens is found at the front of the headlamp. 

8. An LED lamp is light-emitting diode. It has a long service life, is vibration resistant, 

and requires smaller packaging than conventional lamps. 


The Filament in the Light Bulb 




1. Show that fi laments inside incandescent light bulbs heat up as more current fl ows 

through them. 

2. Show that a heated fi lament produces light. 



1,2,3 Life Skills Safety in and around Safety in Electricity and 

the e hous 

heating ystems s 

Lights 

4,5,6 Life Orientation Safety in and around Safety in Electricity and 

the e hous 


Natural ience Sc Electricity Circuits, esistance, r 

conductors 

Heat nergy & E 

Technology Electricity Circuits, esistance, r 

conductors ght Li bulbs 

7,8,9 Technology Electricity Circuits, esistance, r onductors c 

Light bulbs 

Natural ience Sc Electricity Circuits nd esistance a r 

Heat nergy & E 


Resistance, t, hea ght li 

Electrical Technology Electricity & Electronics Drawing & building circuits 

Resistance, bulbs 

Mechanical Technology Electricity Drawing & building circuits. 

Resistance, bulbs 

Engineering Graphics Electricity & Electronics Drawing circuit diagrams 

& esignD 

Questions 

Grade 1,2,3: 

1. Can you touch a light bulb when it is on? 

2. Which bulbs get hotter, fl uorescent or incandescent? 

Grade 4,5,6: 

3. What energy conversions take place when a light bulb comes on? 

4. Do conductors have resistance? 


ME 21/11/12 V7

Questions 

Grade 7,8,9: 

5. What happens to the current if you add more bulbs to a circuit? 

6. What is the function of a resistor? 

Grade 10,11,12: 

7. How is current related to power? 

8. Why is the filament of a light bulb encased in an inert gas? 


1. Wikipedia, 2001, Electrical resistance and conductance, (Updated 16 August 2011) 

Available at: 


2. Tom Harris, 2011, How light bulbs work, Available at: [Accessed 27 August 2011]. 

3. Enchanted Learning, 2010, The invention of the light bulb, Available at: [Accessed 27 August 2011]. 

4. The Lemelson Center, Make a light bulb, Available at: [Accessed 27 August 2011]. 

5. Wikipedia, 2011, Incandescent light bulb, (Updated 22 August 2011) 



1. Sci-Bono exhibit: The filament in the light bulb 

2. In Limbo, What Learned in Chemistry, Available at: [Accessed 23 May 2012] 

3. Tom Harris, 2011, How light bulbs work, Available at: [Accessed 27 August 2011]. 

4. The Lemelson Center, Make a light bulb, Available at: [Accessed 27 August 2011]. 


1. No. It gets hot and you could burn. 

2. Incandescent. 

3. From electrical to heat to light. 

4. Yes. The better the conductor the less the resistance. 

5. The current decreases for the same voltage. 

6. They are used to modify circuits or dissipate electrical energy. 

7. P=I 2 R 

8. The filament reaches very high temperatures and will start combusting in the presence 

of oxygen, so an inert gas, like argon, is used to encase the filament. 



Things Heat up 




1. Show that the fl ow of current generates heat. 

2. Show that the smaller the resistance the greater the heat rate. 

3. Show that a greater energy source produces a higher current. 



1,2,3 Life Skills Safety in and around Safety in Electricity and 

the e hous 


4,5,6 Life Orientation Safety in and around Safety in Electricity and 

the e hous 



Technology Electricity Circuits nd esistance a r 

7,8,9 Technology Electricity Circuits nd esistance a r 


10,11,12 Physical Science Electricity Drawing & building circuits. 

Resistance 

Electrical Technology Electricity & Electronics Drawing & building circuits. 

Resistance 

Mechanical Technology Electricity Drawing & building circuits. 

Resistance 


& esignD 

Questions 

Grade 1,2,3: 

1. If you switch an electric stove plate on, what will you observe after a while? 

2. Why should you not touch a light bulb when it is on? 

Grade 4,5,6: 

3. Which will produce more electric current, one battery or two batteries connected in series? 

4. What are the dangers of element heaters? 


ME 21/11/12 V7

Questions 

Grade 7,8,9: 

5. What is electrical resistance? 

6. Which has a higher resistance, a short or a long wire? 

Grade 10,11,12: 

7. What metal is commonly used in heating systems? 

8. Why do electrical resistors heat up when a current flows through them? 


1. Wikipedia, 2011, Electric Heating, Available at: [Accessed 13 August 2011]. 

2. Wikipedia, 2011, James Prescott Joule, (Updated 13 August 2011), Available at: 


3. G.R. Delpierre and B.T. Sewell, 2011, Heating Effects of Electric Current, Available at: 


4. W.S. Pretzer, 2011, Light Bulb, Available at: [Accessed 13 August 2011]. 

5. Wikipedia, 2011, Resistor, (Updated 13 August 2011) Available at: [Accessed 14 August 2011]. 



2. Miller’s Electrical, 2005, Gallery 2, Available at: [Accessed 14 August 2011]. 

3. G.R. Delpierre and B.T. Sewell, 2011, Heating Effects of Electric Current, Available at: 



1. The plate on the stove is get hotter. 

2. The bulb is hot and you may burn. 

3. Two batteries connected in series. 

4. They may easily ignite furnishings that are close by, especially when they fall over. 

They may also cause serious burns if touched 

5. Electrical resistance is the opposition of the passage of electric current. 

6. A long wire. 

7. Tungsten. 

8. The current collides with the atoms of the wire transferring energy to then and 

the wire then heats up. 


Car Indicators: 




1. Simulate the working of vehicle indicators. 

2. Show the opening and closing of an electric circuit. 

3. Demonstrate the function of a fl asher unit. 

4. Demonstrate a 2-way lever switch. 



1,2,3 Life lls Ski 

Religion Christmas ghtsLi 

Transport Safety, obotsR 

4,5,6 Life ientation Or 

Religion Christmas ghtsLi 

Transport Safety, obotsR 

Natural Science Electricity Picture of circuit 

7,8,9 Technology Electricity Drawing 

Safety 

lding & ircuits, bui c 

Natural Science Electricity Drawing & building circuits, 

Safety 

10,11,12 Physical Science Electricity, Drawing & building circuits, 

Electronics. Flashing ircuits. c 

Matter terial. & Conductors, Ma emi-conductors s 

& nsulators. i 

Electrical Technology Electricity Drawing & building circuits, 

& lectronics E Flashing ircuits c 

Mechanical echnology T 

Electricity Car cator Indi 

Engineering Graphics Electricity & Drawing circuit diagrams 

esign & D 

Electronics 

Questions 

Grade 1,2,3: 

1. Where do you fi nd fl ashing lights in our daily life? 

2. What is the colour of an ambulance’s fl ashing light? 

Grade 4,5,6: 

3. What colour fl ashing lights do we use to indicate caution? 

4. Why do we use fl ashing lights? 


ME 21/11/12 V7

Grade 7 – 12: 

5. Draw a circuit diagram of the vehicle indicator circuit. 

6. Is the vehicle indicator circuit a parallel or a series circuit? 

Grade 10,11,12: 

7. What makes the bimetallic strip in the flasher unit bend when it is heated? 


1. Robots, emergency vehicles, police, Christmas lights, signage. 

2. Red. 

3. Blue – police; Orange – construction, towing, vehicle indicators. 

4. To attract your attention. 

5. Circuit diagram should be based on the circuit below. Complexity of the circuit 

is grade specific. Remember that “ground” closes the circuit since this is attached 

to the negative pole of the battery. 

5. Circuit diagram should be based on the circuit below. Complexity of the circuit is grade 

specific. Remember that “ground” closes the circuit since this is attached to the negative 

pole of the battery. 

6. Difference in expansion and contraction of the two fused metals causes the bimetallic strip 

to bend when it is heated or cooled 

References and Interesting Websites 

1. Karim Nice, 2011, How Turn Signals Work, Available 

at: [Accessed 30 April 2011]. 

2. Wikipedia, 2011, Automotive Lighting, (Updated 

25 April 2011) Available at: 


3. Isaiah David, 2011, How Does a Car’s Signal Lights 

Work, Available at: 


Figure 3: Indicator Circuit 

(http://auto.howstuffworks.com/turn-signal.htm) 


1. Sci-bono exhibit. 

2. Wikipedia, 2011, Automotive Lighting, (Updated 25 April 2011) Available at: [Accessed 30 April 2011]. 

3. Karim Nice, 2011, How Turn Signals Work, Available at: [Accessed 30 April 2011]. 


The More Lights you Switch 

on the More Current you need 




1. Show that the greater the load is on the circuit, the more current is required. 

2. Show that the greater the load is on the circuit, the more energy is required. 



1,2,3 Life Skills Safety in and around Safety in Electricity 

the e hous 

Energy avings 

4,5,6 Life Orientation Safety in and Safety in electricity 


Natural Science Electricity Circuits and power sources 

Energy Energy aving s 

Technology Electricity Circuits nd awer 

poources 

s 

7,8,9 Technology Electricity Circuits nd awer 

poources 

s 

Natural ience Sc Electricity Circuits nd awer 

poources 

s 

Ohm’s w la 


Ohm’s w la 

Industrial hemistry c Energy ources s 



& esignD 

Questions 

Grade 1,2,3: 

1. What is the purpose of the generator in the exhibit? 

2. Why should you not leave the lights on when they are not needed? 

Grade 4,5,6: 

3. Do factories use more electricity than homes? Why? 

4. Which uses more electricity, an oven or a computer? Why? 


ME 21/11/12 V7

Questions 

Grade 7,8,9: 

5. Which consumes more power, a 1000W hair dryer or a 1000W microwave oven 

if they are left on for the same time? 

6. In which circuit will two light bulbs shine brighter, in one where they are connected 

in series to a battery, or in one where they are connected in parallel to the battery? 

Grade 10,11,12: 

7. What could do to your geyser so that it consumes less energy? 

8. What is the difference between a compact fluorescent globe and tungsten filament 

globe that produce the same amount of light? 


1. Wikipedia, 2011, Electricity, (Updated 13 August 2011) Available at: [Accessed 18 August 2011]. 

2. Marshall Brain, William Harris and Robert Lamb, 2011, How Electricity Works, Available 

at: [Accessed 18 August 2011]. 

3. NDT Resource Center, 2011, Electricity, Available at: [Accessed 18 August 2011]. 



2. Southern Company, 2011, Plants, Poles and Plugs, Available at: 

 



1. To produce electricity. 

2. You are wasting energy. 

3. Yes. They usually have large machines that consume more electricity. 

4. An oven. It requires a lot of current to heat up. 

5. They consume the same power, 1000W, if they are on for the same time. 

6. The circuit with the bulbs connected in parallel. 

7. Turn the thermostat down. 

8. The compact fluorescent uses less energy because it produces less heat for the 

same amount of light. 


Ohm’s Law Demonstrator 




1. Demonstrate the relationship between voltage current and resistance in a circuit, 

i.e. Ohm’s law. 




the ehous 

4,5,6 Life Orientation Safety in and around Safety in electricity 

the e hous 

Natural Science Electricity Drawing and building circuits 

Technology Electricity Drawing nd alding 

bui ircuits c 

7,8,9 Technology Electricity Drawing 

Calculations 

lding & ircuits bui c 

Natural Science Electricity Drawing & building circuits 

Calculations 


Calculations 


Mechanical Technology Electricity Circuits and car battery 

Questions 

Grade 1,2,3: 

1. Give a few examples of things that resist electricity fl ow. Note that they normally heat up. 

2. Will a battery with a higher voltage give more electricity fl ow or less electricity fl ow? 

Resistance = Voltage 

Grade 4,5,6: 

3. What is the SI unit for resistance? 

4. From Ohm’s law we know that . 

Current 

Calculate the resistance of a light bulb that has a voltmeter reading of 6V and 

an ammeter reading of 2A. 

Grade 7,8,9: 

5. What can affect the Ohm’s law behavior of a normal ohmic resistor? 

6. Calculate the current in a circuit that has three resistors of 2Ω, 3Ω and 4Ω connected in 

series to a 12V battery. 


ME 21/11/12 V7

Grade 10,11,12: 

7. You have 2 resistors of 3Ω and 4Ω in parallel to a 12V battery. What value resistor can you 

place in series to reduce the current to 5A? 

8. What power will be dissipated in each case? 


1. Reocities, Georg Simon Ohm, Available at: [Accessed 06 September 2011]. 

2. All About Circuits, 2011, How voltage, current, and resistance relate, 


[Accessed 08 September 2011]. 

3. Wikipedia, 2011, Ohm’s law, (Updated 31 August 2011) Available at: [Accessed 05 September 2011]. 

4. Jerry Silver, 2011, Ohm’s Law: Running into Resistance, Available at: [Accessed 07 September 2011]. 



2. Reocities, Georg Simon Ohm, Available at: [Accessed 06 September 2011]. 

3. RM Cybernetics, What are volts, amps & watts etc, Available at: [Accessed 07 September 2011] 

and Wikipedia, 2011, Ohm’s law, (Updated 31 August 2011) Available at: [Accessed 05 September 2011]. 


1. A kettle element, a stove plate, a bar heater, a light bulb filament. 

2. More electricity flow. 

3. The ohm (Ω). 

4. R=3Ω. 

5. Temperature variations. 

6. 

7. 

Total R=9Ω, so I = 12/9 = 1.33A. 

R 1 x R 2 3 x 4 12 

Total R required = 12/5 = 2.4Ω. For parallel resistors R T = = = = 1.714Ω. 

R 1 + R 2 

3 + 4 7 

Therefore resistor in series required = 2.4 – 1.714 = 0.686Ω. 

9. In the first case I = 12 / 1.714 = 7A, therefore P = 12 x 7 = 56 watts. 

In the second case P = 12 x 5 = 60 watts. 


More Batteries Please! 




1. Show that more batteries give more power. 

2. Batteries have two terminals a positive and a negative. 

3. In a series connection the positive of one battery must touch the negative of the other battery. 



1,2,3 Life Skills Energy Safety n 

batteries 

lectricity i E nd a 

4,5,6 Life Orientation Safety n nd i a Safety n ectricity i el 


Natural ience Sc Electricity Circuits nd atteries 

ba 

Technology Electricity Circuits nd atteries 

ba 

7,8,9 Technology Electricity Circuits nd atteries 

ba 


ba 

10,11,12 Physical Science Electricity Safety in Electricity and 

batteries 

Electrochemistry Electrochemical ells c 

Industrial hemistry c Batteries 

Electrical Technology Electricity & Electronics Drawing & building circuits, 

tteries ba 


Questions 

Grade 1,2,3: 

1. If you have more batteries will you have more energy? 

2. How many electrical contacts or terminals does a battery have? 

Grade 4,5,6: 

3. Where are the positive and the negative terminals of an AA battery? 

4. Which terminalsmuch touch when you are joining two batteries in series? 

Grade 7,8,9: 

5. If you add 6 batteries in series of 1.5V each what is the total voltage? 

6. A light bulb has a rating of 12V. Which battery will light up the light bulb, 

a car battery ortorch (AA) battery? 


ME 21/11/12 V7

Grade 10,11,12: 

7. How will you connect two batteries of the same voltage to increase the capacity 

(amp hour) of the batteries but keep the voltage the same? 

8. How would you connect 4 batteries each having a voltage of 1.2V in order 

to achieve a total voltage of 2.4V? 


1. Wikipedia, 2011, Battery (electricity), (Updated 9 April 2011), Available at: [Accessed on 20 April 2011]. 

2. Wikipedia, 2011, Electrochemical cell, (Updated 25 March 2011), Available at: [Accessed 30 April 2011]. 

3. Giorgio Carboni, January 1998, Experiments in Electrochemistry, Available at: [Accessed 01 May 2011]. 

4. Wikipedia, 2011, Daniel cell, (Updated 19 July 2011), Available at: [Accessed 06 August 2011]. 

5. AllAboutBatteries.com, (Updated 12 January 2011), Available at: [Accessed 06 August 2011]. 

6. Isidor Buchmann, 2011, Learning the Basics About Batteries, Available at: [Accessed 08 August 2011]. 



2. Battery University, 2011, Series and Parallel Configurations, Available at: 


3. Battery University, 2011, Series and Parallel Configurations, Available at: 



1. Yes. 

2. Two. A positive and a negative. 

3. The positive is at the top and the negative is at the bottom. 

4. The positive of one must touch the negative of the other. 

5. 6 x 1.5 V = 9 V 

6. The car battery because it is a 12V battery. You could use 8 X 1.5V AA batteries. 

7. Connect the two batteries in parallel. 

8. Connect them in combinations of series and parallel. Make 2 pairs of series connections. 

Now connect the pairs to each other in parallel. 

http://cr2032.co/series-parallel-article.html 


Selecting the Right Battery 




1. Show that the correct amount of energy must be supplied to an appliance for it to function. 

2. That the voltage of a battery is more important than its shape or size. 

3. That current fl ows in a certain direction. 




batteries 


4,5,6 Life Orientation Safety n nd i a Safety n ectricity i el 



ba 


ba 


ba 


ba 

10,11,12 Physical Science Electricity Safety in Electricity and 

batteries 




tteries ba 


Questions 

Grade 1,2,3: 

1. Do bigger batteries always have more energy than smaller ones? 

2. Can you use a battery that is damaged and has leaked? 

Grade 4,5,6: 

3. What is the voltage of a car battery? 

4. What is the equivalent amount of 1.5V batteries will you need to start a car? 

Grade 7,8,9: 

5. Can you use a car battery to operate a 3V doorbell? 

6. What is the difference between primary and secondary batteries? 

Grade 10,11,12: 

7. What is the most common type of battery used in cars? 

8. What type of cell is a rechargeable battery when it is being charged? 


ME 21/11/12 V7

Selecting The Right Battery?: 


1. Wikipedia, 2011, Battery (electricity), (Updated 9 April 2011), Available at: [Accessed on 20 April 2011]. 

2. Wikipedia, 2011, Electrochemical cell, (Updated 25 March 2011), Available at: [Accessed 30 April 2011]. 

3. Giorgio Carboni, January 1998, Experiments in Electrochemistry, Available at: [Accessed 01 May 2011]. 

4. Wikipedia, 2011, Daniel cell, (Updated 19 July 2011), Available at: [Accessed 06 August 2011]. 


6. Isidor Buchmann, 2011, Learning the Basics About Batteries, Available at: [Accessed 08 August 2011]. 



Table References 


2. Isidor Buchmann, 2011, Battery Developments, Available at: [Accessed 08 August 2011]. 


1. No. 

2. No. 

3. 12V. 

4. 8 X 1.5V batteries connected in series will give a voltage of 12V needed to start a car. 

5. No. It will damage the bell because the car battery is 12V. 

6. Primary batteries (disposable batteries) cannot be recharged. 

Secondary batteries (rechargeable batteries) can be recharged and used many times. 

7. The lead acid battery as it is the cheapest to manufacture. 

8. An electrolytic cell. 

http://cr2032.co/series-parallel-article.html 


The Current Only Flows when 

the Appliance is Connected 

to a Battery 




1. Show that an electric potential difference or energy source is required for current to fl ow. 

2. Show that an appliance will only work if it is connected to an energy source. 

3. Show that the greater the load or resistance on your source the weaker the current. 



1,2,3 Life Skills Energy Safety n lectricity i E 

and atteries b 


the ehous 


ba 


ba 


ba 


ba 

Resistance nd a s Ohm’ w la 


Batteries 

Resistance nd a s Ohm’ w la 



Energy ources s 


batteries 



& esignD 

Questions 

Grade 1,2,3: 

1. Where does the energy comes from to light the globe of a hand torch? 

2. Will a cell phone operate if you remove its battery? Why not? 


ME 21/11/12 V7

Questions 

Grade 4,5,6: 

3. Where does the electricity come from to make your appliances at home work? 

4. How does electricity get to an appliance from the source? 

Grade 7,8,9: 

5. How many torch batteries would you need to light a bulb rated 4.5 V? 

6. What is electric current? 

Grade 10,11,12: 

7. What is the difference between AC and DC current? 

8. Can you connect a DC appliance to an AC source? 


1. D Bondar, 2011, The History of Electric Current, Available at: 

 


2. Wikipedia, 2011, Electric Current, (Updated 7 August 2011), Available at: 


3. Physics4kids.com, 2011, Alternating Current, Available at: [Accessed 13 August 2011]. 

4. Tony R. Kuphaldt, 2002, Conventional Versus Electron Flow, Available at: 

 




2. MS Mcgartland, 2011, Flow of Electrons, Available at: [Accessed 14 August 2011]. 

3. Physics4kids.com, 2011, Alternating Current, Available at: 



1. From the batteries. 

2. No, there is no energy to make it work. 

3. From a power generating station. (E.g. Eskom power station) 

4. Through conducting wires that are connected from the source to the appliance. 

5. Three batteries connected in series. Each battery is 1.5 V, which adds up to 4.5 V 

if connected in series. 

6. A flow of charge. 

7. AC current is continually alternating its direction, whereas DC current only flows 

in one direction. 

8. Not directly. You could use a transformer to convert the current from AC to DC and 

then connect to the appliance. 


A Short Journey into Electricity 




1. Show the principle behind the working of a motor. 

2. Show one of the effects of a current. 




the ehous 


the ehous 

Natural ience Sc Electricity All 

Technology Electricity All 

7,8,9 Technology Electricity All 

Natural ience Sc Electricity All 

10,11,12 Physical Science Electricity All 

Electrical Technology Electricity & Electronics All 

Mechanical echnology T Electricity All 

Questions 

Grade 1,2,3: 

1. In what ways do we use electricity? 

2. Is lightning electricity? 

Grade 4,5,6: 

3. Is electrical energy created at power stations? 

4. What units are used to measure the amount of power consumed by light bulbs? 

Grade 7,8,9: 

5. How is lightning formed? 

6. Does an electric heater fi lament have a high or a low resistance? 

Grade 10,11,12: 

7. On what principle does an electric motor work? 

8. What is electrolysis? 


ME 21/11/12 V7


1. Forte Electric Inc., 2005, The history of electricity, 


2. Ducksters, 2011, Kids science: uses of electricity, 



3. Wikipedia, 2011, Electricity, (Updated 13 August 2011) 



1. Sci-Bono exhibit 

2. Wikipedia, 2011, Electric charge, (Updated 19 August 2011) 

Available at: [Accessed 02 September 2011]. 

3. http://www.firstaidandsafetyonline.com/prod_details~catid~382~id~16989.asp 


1. It is used to power all sorts of appliances e.g. cell phones, computers, lights, ovens, cameras. 

2. Yes. It is a discharge of static electricity. 

3. No. Energy cannot be created. One form of energy is converted to electrical energy. 

4. Watts. 

5. The collision of water droplets in the cloud causes them to become charged. 

Electrons that have been knocked off moisture molecules move to the bottom of the cloud 

making it negative. Positive molecules move to the top of the cloud making the top part 

positive. The charged cloud causes the around it to become ionized i.e. a plasma. The ionized 

air is a path for electrons to flow from the clouds to the earth. The discharge of electrons 

from the cloud occurs as lightning. 

6. A high resistance. 

7. Electromagnetic induction. 

8. Electrolysis is a chemical change produced by passing an electric current through a liquid or 

a solution that contains ions. 


Beware of a Short Circuit 




1. Demonstrate what constitutes a short circuit. 

2. Highlight the dangers of short circuits. 




the ehous 


the ehous 


Safety n ectricity i el 



7,8,9 Technology Electricity Circuits 






Mechanical echnology T Electricity Circuits 

Questions 

Grade 1,2,3: 

1. What could happen if you use an appliance with an electrical cord that is damaged? 

2. What is the danger of electric wire that is placed under carpets? 

Grade 4,5,6: 

3. How can you tell if an appliance has shorted? 

4. You have a circuit with three lamps in series. One of the lamps stops working and 

this causes the other two lamps to switch off. What can you do to the circuit to get these 

two lamps to come on? 

Grade 7,8,9: 

5. When you are joining two 3-core wires, what should you ensure at the joint? 

6. Comment on the circuit diagram below. 


ME 21/11/12 V7

Grade 10,11,12: 

7. What can you measure to determine if two wires are touching? 

8. What can you add to a circuit to protect against short circuits? 


1. Wikipedia, 2011, Short circuit, (Updated 22 August 2011) Available at: [Accessed 06 September 2011]. 

2. Elizabeth Sluder and Daniel Friedman, 2011, What is an electrical circuit, Available at: [Accessed 06 September 2011]. 

3. NFEC Singapore Government, Commercial Fire, (Updated 19 August 2011) Available at: [Accessed 06 September 2011]. 

4. Irma Venter, 12 February 2010, Honda SA in safety recall after fire tragedy,Available at: 

[Accessed 06 October 2011]. 

5. Wikipedia, 2011, Power supplies, (Updated 15 August 2011) Available at: [Accessed 06 September 2011]. 

6. Wikipedia, 2011, Circuit breaker, (Updated 03 September 2011) Available at: [Accessed 06 September 2011]. 

7. Wikipedia, 2011, Fuse (electrical), (Updated 25 August 2011) Available at: [Accessed 06 September 



2. Independent Online, 29 January 2010, Honda SA part of worldwide Jazz anti-fire recall, 

Available at: [Accessed 06 October 2011]. 

3. Digi-Key cooperation, 2011, Fuses, Available at: [Accessed 06 September 2011] 

and Focus Technologies, 2011, Miniature circuit breaker, Available at: 


4. 123RF, Electrical failure in power outlet isolated, 2011, Available at: 



1. Any exposed wires could touch other wires causing a short circuit. 

2. The wires could get worn from walking over them. This can lead to the insulation coming 

of the wires and the wire touching each other. This will result in a short circuit. 

Any sparks from the short circuit could cause a fire. 

3. There might be a spark, or the appliance could get hot or a fuse might be blown. 

4. Connect a wire across the lamp that is not working. 

5. Ensure that the joined wires are insulated and are not able to cause a short 

circuit between wires. 

6. When the circuit is closed there will be a short circuit. Current will not flow 

through the resistor. 

7. Measure the resistance across the two wires. If there is a reading on the multi meter 

then they are touching. 

8. Add a fuse, circuit breaker or earth leakage breaker. 


Electricity Safety 




1. Demonstrate some hazardous electrical situations. 




the ehous 


the ehous 

Natural ience Sc Electricity Circuits, urrent, c oltage v 


Technology Electricity Circuits, urrent, c oltage v 


7,8,9 Technology Electricity Circuits, urrent, c oltage v 


Natural ience Sc Electricity Circuits, urrent, c oltage v 



Current, oltagev 



Questions 

Grade 1,2,3: 

1. Should you use a hair dryer with wet hands? 

2. Where should you not fl y a kite? 

Grade 4,5,6: 

3. What is the fi rst thing you must do before changing a light bulb? 

4. Why are overhead power lines dangerous? 

Grade 7,8,9: 

5. What is the purpose of the earth (ground) wire in an electric circuit? 

6. What is the danger of using a 2-pin plug on a 3-core electric wire? 

Grade 10,11,12: 

7. What should you do when someone is experiencing an electric shock? 

8. What is the danger of capacitors in appliances? 


ME 21/11/12 V7


1. Oklahoma State University, Electrical safety, (Update 28 March 2011) 

Available at: 


2. The Electrical Safety Council, 2011, Electricity and how to use it safely, 




2. Oklahoma State University, Electrical safety, (Update 28 March 2011) 

Available at: 



1. No. The water could case a short circuit and you could get an electric shock. 

2. Near overhead power lines. 

3. Make sure that the power if off. 

4. Because they are not insulated and have a high voltage. 

5. The earth wire is used to protect against dangerous voltages incase the electrical 

insulation fails. It is also used to limit the build up of static electricity. 

6. The appliance will not be earthed. 

7. See Response to Electrical Emergencies section 

8. Even when the power is switched off they carry stored charged. 

They must be discharged before repair work can be performed on them. 


The Human Battery 




1. Show the fl ow of current. 

2. Show that current can be indicated by means of an ammeter or the glowing of a lamp. 

3. Demonstrate that human perspiration can function as the acid in a battery. 

4. Show that human perspiration is acidic. 

5. Show that current fl ows through the human body. 



1,2,3 Life skills Energy Electricity nd atteries 

ba 

4,5,6 Life Orientation Safety in and Body conducts electricity 



ba 


ba 


ba 


ba 

10,11,12 Physical Science Electricity Circuits and batteries 

Human body s attery 

a ba 

Electrochemistry Electrochemical ells 

Ionization 

Electrolytes 

c 



batteries 


Questions 

Grade 1,2,3: 

1. Do torch batteries store energy? 

2. Will you shock from a torch battery? 

Grade 4,5,6: 

3. Is your body a battery? 

4. Name some energy sources of electricity? 


ME 21/11/12 V7

Grade 7,8,9: 

5. Would the experiment work if humans were not conductors of electricity? 

6. What is an electric current? 

Grade 10,11,12: 

7. What is the origin of the current in this experiment? 

Does it come from inside the human body? 

8. Would this experiment work if our sweat was not acidic? Why? 


1. Brain, M. Bryant,C,W. 2011, How Batteries Work, Available at: [Accessed 20 April 2011]. 

2. Wikipedia, 2011, Battery (electricity), (Updated 9 April 2011) Available at: [Accessed on 20 April 2011]. 

3. Wikipedia, 2011, Electrochemical cell, (Updated 25 March 2011) Available at: < http:// 

en.wikipedia.org/wiki/Electrochemical_cell> [Accessed 30 April 2011]. 

4. Giorgio Carboni, January 1998, Experiments in Electrochemistry, Available at: < http://www. 

funsci.com/fun3_en/electro/electro.htm> [Accessed 01 May 2011]. 




3. http://en.wikipedia.org/wiki/Battery_(electricity) 


1. Yes. When you switch a torch on the light goes on. 

2. No, there is not enough energy to shock you. 

3. No. It only acts as the acid of the battery. 

4. Batteries, generators, electricity power stations. 

5. No. Although there would be a voltage difference between the plates, 

the circuit would be open and no current would flow. 

6. It is a flow of charges. 

7. No. It originates from the difference in charge between the copper and aluminium plates. 

This results in a voltage difference between the two plates and thus a current is able to flow. 

8. No. There would be no reaction with the copper and aluminium plates and therefore no 

build up of charges. 


What is Inside a Battery? 




1. Show what makes up a cell of a battery. 

2. To show that electrical energy may be obtained from a chemical reaction. 




batteries 



the ehous 


ba 


ba 


ba 


ba 

10,11,12 Physical Science Electricity Drawing & building circuits, 

batteries 




batteries 


Questions 

Grade 1,2,3: 

1. Do batteries store energy? 

2. Will you shock from a torch battery? 

Grade 4,5,6: 

3. How many volts is a car battery? 

4. What are the environmental concerns around the use of batteries? 

Grade 7,8,9: 

5. What is the negative end of a battery called? 

6. What type of energy conversion takes place in a battery? 

Grade 10,11,12: 

7. What separates the half-cells of an electrochemical cell? 

8. What is the EMF of a cell? 


ME 21/11/12 V7

What is Inside a Battery?: 


1. Wikipedia, 2011, Battery (electricity), (Updated 9 April 2011), Available at: 

[Accessed on 20 April 2011]. 

2. Wikipedia, 2011, Electrochemical cell, (Updated 25 March 2011), Available at: 


3. Giorgio Carboni, January 1998, Experiments in Electrochemistry, Available at: 


4. Wikipedia, 2011, Daniel cell, (Updated 19 July 2011), Available at: 


5. AllAboutBatteries.com, (Updated 12 January 2011), Available at: 


6. Isidor Buchmann, 2011, Learning the Basics About Batteries, Available at: 




2. Creative Commons Attribution Share-Alike, 2011, Electrochemical cells, 



3. HyperPhysics, Voltaic Cells, Available at: [Accessed 07 August 2011]. 

4. Hila Research Center, Available at: [Accessed 07 August 2011]. 


1. Yes. When you use it in an appliance it makes it work. 

2. No, there is not enough energy to shock you. 

3. 12 V. 

4. Toxic chemical waste and toxic metal pollution. They are also harmful if swallowed. 

5. Anode. 

6. Chemical energy to electrical energy. 

7. A salt bridge. 

8. It is the electromotive force of the cell. It is the ability of a cell to drive electric current. 







1. Show an example of electrolysis. 

2. Show that electrolysis requires a current. 

3. Show that some liquids can conduct electricity. 



1,2,3 Life Skills Energy Safety n lectricity i E nd a 

batteries; ses ga 

4,5,6 Life Orientation Safety in and Safety in electricity 



Gases 

nd atteries 

ba 

Technology Electricity Circuits; urrent; c tteries ba 


ba 


ba 

10,11,12 Physical Science Electricity 

Energy onversion c 

Drawing & building circuits, 

batteries 

Electrochemistry Electrochemical ells; c 

electrolysis 

Industrial hemistry c Batteries; ectroplating el 

Chlor li Alka ocess pr 


batteries; 

charges 

ectroplating; el 


Engineering Graphics 

& Design 

Electricity & Electronics Drawing circuit diagrams 

Questions 

Grade 1,2,3: 

1. Where does the energy comes from to light the globe of a hand torch? 

2. Will a cell phone operate if you remove its battery? Why not? 


ME 21/11/12 V7

Questions 

Grade 4,5,6: 

3. Give some examples of items that have been plated. 

4. Is hydrogen a solid, liquid, or gas? 

Grade 7,8,9: 

5. What type of energy conversion is taking place in an electrolytic cell? 

6. Where does the hydrogen that is released in the exhibit come from? 

Grade 10,11,12: 

7. What is the difference between a galvanic and an electrolytic cell? 

8. Is the chemical reaction in an electrolytic cell spontaneous? 


1. Wikipedia, 2011, Electrolysis, (Update 24 July 2011) Available at: [Accessed 14 August 2011]. 

2. Tilak V. Bommaraju, Paul J. Orosz, and Elizabeth A. Sokol, November 2001, 

Brine Electrolysis, (Updated September 2007, Available at: [Accessed 15 August 2011]. 

3. G.R. Delpierre and B.T. Sewell, 2011, Electrolysis, Available at: 


4. SouthAfrica.info, September 2011, Manufacturing in South Africa, Available at: 

 




2. Electrical Reply, 07 June 2006, Hydrogen from water electrolysis, Available at: 

 


3. California Energy Commission, 2008, H2O Electrolysis, Available at: 



1. Yes, otherwise the experiment would not work. 

2. That there is gas in the liquid. 

3. Silver or gold plated jewelry; chrome plated mag wheels; galvanized nails. 

4. A gas. It is seen as bubbles in the solution. 

5. Electrical to chemical energy. 

6. It comes from the water, which consists of Hydrogen and Oxygen atoms. 

7. In a galvanic cell chemical energy is converted into electrical energy. 

In an electrolytic cell it is the reverse. 

8. No. The reverse is spontaneous. 


Jumping Disc 




1. Show the working of a capacitor. 

2. Show the transfer of energy from electrical to kinetic. 



1,2,3 Life Skills Safety in and around Electricity 

the e hous 

4,5,6 Life Orientation Safety in and around Electricity 

the ehous 

Natural ience Sc Electricity Energy torage s 




Energy Energy torage s 

Energy onversion c 



Capacitors 

Electrical Technology Electricity Drawing, building and 

& lectronics E 


Capacitors 


& esignCapacitors 

D 

Questions 

Grade 1,2,3: 

1. A capacitor is a device that stores electrical energy. 

Name another device that can store electrical energy? 

2. What can you use electrical energy for? 

Grade 4,5,6: 

3. In what types of appliances will you fi nd capacitors? 

4. What does “charging a device” when dealing with electricity, mean? 

Grade 7,8,9: 

5. What type of energy conversion is taking place in the exhibit? 

6. What should you ensure before you touch a capacitor? 

Grade 10,11,12: 

7. What is the SI unit for capacitance? 

8. What is the total capacitance if two capacitors of 2 μF and 4 μF where connected in series? 


ME 21/11/12 V7

Jumping Disc: 


1. M. Brain and C.W. Bryant, How Capacitors Work, 17 September 2007, Available at: 


2. Wikipedia, 2011, Capacitor, (Updated 13 August 2011) Available at: [Accessed 16 August 2011]. 

3. Howstuffworks.com, 2011, How do touch-screen monitors know where you’re touching? 



4. Tracy V. Wilson, 2011, How the iPhone Works, Available at: [Accessed 17 August 2011]. 

5. Pakistan Science Club, 2011, Make Your Own Capacitor, Available at: 

 




2. Tracy V. Wilson, 2011, How the iPhone Works, Available at: [Accessed 17 August 2011]. 

3. M. Brain and C.W. Bryant, How Capacitors Work, 17 September 2007, Available at: 


4. Pakistan Science Club, 2011, Make Your Own Capacitor, Available at: 



1. A battery. 

2. For making appliances work, e.g. television. 

3. Televisions, radios, computers, etc. 

4. It means adding energy to the device. 

5. Electrical to mechanical energy (kinetic). 

6. Ensure that it is completely discharged. 

7. Farad (F) 

8. 1 

CT 

1 1 1 1 3 

= = = = = 

C1 

C2 

2 4 4 

1 4 

CT 

3 

= = 1,333 μF = 1,333 x 10-6 F 


When a current fl ows, 





1. Show that a current is able to induce a magnetic fi eld in a conductor. 

2. Shows that electricity and magnetism are related. 




the e hous 

Magnets Attraction epulsion &r 


the e hous 

Magnetism Attraction epulsion &r 

Natural ience Sc Electricity Current 

Magnetism Attraction epulsion & r 

Technology Electricity Current 


7,8,9 Technology Electricity gnetism & ma Electromagnet 

Natural ience Sc Electricity Magnetic eld 

with current 

ssociated fi a 

Magnetism Magnetic eld fi 

10,11,12 Physical Science Electromagnetism Magnetic fi eld associated 

with current 

Electromagnetic nduction i 

Electrical Technology Electricity & Electronics Electromagnet 

Questions 

Grade 1,2,3: 

1. What can magnets do? 

2. Will a magnet stick on a fridge or a brick wall? 

Grade 4,5,6: 

3. What is the difference between the 2 poles of a magnet? 

4. What is a magnetic fi eld? 


ME 21/11/12 V7

Questions 

Grade 7,8,9: 

5. What happens to a compass needle when it is near a wire carrying an electric current? 

6. What is an electromagnet? 

Grade 10,11,12: 

7. Can the opposite happen, i.e. can a magnet cause a current to flow? 

8. What is electromagnetic radiation? 


1. Jefferson Lab, How do I make an electromagnet, 


2. C. Byrne, 15 January 2011, A Brief History of Electromagnetism, 


3. Wikipedia, 2011, History of electromagnetic theory, (Updated 20 August 2011) Available at: 


4. Wikipedia, 2011, Electromagnet, (Updated 21 August 2011) 


5. Wikipedia, 2011, Electromagnetic radiation, (Updated 20 August 2011) 



6. Wikipedia, 2011, Electromagnetism, (Update 17 August 2011) 




2. Wikipedia, 2011, Electromagnet, (Updated 21 August 2011) 


3. Visualization, 2011, Magnetic field of a solenoid, 



4. Jefferson Lab, How do I make an electromagnet, 



1. They can attract and repel some objects. 

2. To a fridge. 

3. The one attracts and the other repels the same object. 

4. The space around a magnet that will attract or repel objects. 

5. It will be deflected. 

6. It has a metal core, which is magnetized when a current flows through a coil around the core. 

7. Yes. This is the principle of the generator. 

8. It is a type of energy that has electric as well as magnetic properties. 


The Motor Effect 




1. Show the principle behind the working of a motor. 

2. Show one of the effects of a current. 



1,2,3 Life Skills Safety in and around Motors in appliances 

the ehous 

4,5,6 Life Orientation Safety in and around Motors in appliances 

he t ehous 


& echnology T 

Magnetism Attraction nd epulsion a r 

Forces Motors n ppliances i a 

Energy Energy hangec 

7,8,9 Natural Science Electricity, magnetism Motors 

& echnology T 

& orce f 

10,11,12 Physical Science Electricity, magnetism The motor effect 

& orce f 

Electrical Technology Electricity & Magnetism AC and DC motors 

Mechanical Technology Electricity AC and DC motors 

Questions 

Grade 1,2,3: 

1. Give a few examples of which devices operate with electric motors? 

2. Why should an electric fan have a grill in front of it? 

Grade 4,5,6: 

3. What is the energy change in an electric fan? 

4. What type of force does a motor produce? 

Grade 7,8,9: 

5. What do we use a force for? 

6. What is torque? 

Grade 10,11,12: 

7. What is the difference between an AC and DC motor? 

8. What turns the engine of a car on startup? 


ME 21/11/12 V7


1. Wikipedia, 2011, Electric motor, (Update 26 August 2011) 


2. Brain Marshall, How Electric Motors Work, 01 April 2000, 


3. Eric Seale, 12 November 2001, DC motors – How they work, (Updated 9 July 2003) 

Available at: 


4. Museum of Science and Industry, Chicago, 2011, Build an Electric Motor, 


5. Squidoo, 2011, The world’s smallest electric motor, Available at: 



1. Sci-Bono exhibit: The motor effect 

2. Sci-Bono exhibit: The principle behind the motor 

3. Sci-Bono exhibit: Using a current to make a magnet rotate 

4. Squidoo, 2011, The world’s smallest electric motor, Available at: 


5. GR Delpierre and BT Sewell, 2011, Electric Machines, Available at: [Accessed 04 October 2011]. 

6. Antonine Education Website, 2011, Deflecting Electrons, Available at: 


7. Museum of Science and Industry, Chicago, 2011, Build an Electric Motor, Available at: [Accessed 28 August 2011]. 

8. Museum of Science and Industry, Chicago, 2011, Build an Electric Motor, Available at: [Accessed 28 August 2011]. 


1. Hair dryer, fan, sewing machine, food processor, drill, etc. 

2. To stop people from putting their hand in the fan. 

3. Electrical to mechanical to wind. 

4. A turning force. 

5. For doing work. 

6. It is a turning force. 

7. The starter motor. 


Electromagnetic Induction 

and Transformers 




1. Show an example of transformation of electricity from AC to DC. 

2. Show electromagnetic induction used in transformers. 

3. Show stepping down and stepping up of voltage. 




the e hous 

Electricity ources. s 



the e hous 





Energy change Power Stations 

Generators 


Generation& oltagev 


7,8,9 Technology Electricity Power Stations 

& gnetism ma 

Electricity 

& ransformers t 

ators gener 

Natural ience Sc Electricity Current ssociated a th wi 

magnetic eld 

Induction 

fi 


10,11,12 Physical Science Magnetism Magnetic fi eld / fl ux 

Electricity AC nd C a D ators gener 

Electrical Technology Electricity 


Power Station 

AC and DC generators 

& gnetism Ma 


Mechanical Technology Electricity AC and DC generators, 

alternators& ransformers 

t 


ME 21/11/12 V7

Questions 

Grade 1,2,3: 

1. Which is more dangerous, a torch battery or household electrical sockets? 

2. Why must a cell phone charger be disconnected when not in use? 

Grade 4,5,6: 

3. What amount of voltage is supplied to household electricity? 

4. If you have a 1000V power supply, what will you use to get to 220V? 

Grade 7,8,9: 

5. What are AC and DC? 

6. Is a cell phone charger a transformer? 

Grade 10,11,12: 

7. What is mutual induction? 

8. A primary coil of a step-down transformer has two thousand turns. How many turns will there 

be on the secondary coil if the voltage is stepped down from 240V to 12V? 


1. Wikipedia, 2011, Transformer, (Updated 23 August 2011) 


2. C.R. Nave, 1997, Electricity and Magnetism, Available at: [Accessed 26 August 2011]. 

3. All About Circuits, What is alternating current, Available at: [Accessed 26 August 2011]. 

4. All About Circuits, Build a transformer, Available at: [Accessed 26 August 2011]. 

5. Wikipedia , 2011, War of Currents, (Updated 20 August 2011) Available at: [Accessed 26 August 2011]. 



2. All About Circuits, What is alternating current, Available at: [Accessed 26 August 2011]. 

3. Wikipedia, 2011, Transformer, (Updated 23 August 2011) Available at: [Accessed 26 August 2011]. 

4. All About Circuits, Build a transformer, Available at: [Accessed 26 August 2011]. 


1. Household electrical sockets. 

2. To save electricity. 

3. 220V. 

4. A transformer. 

5. Alternating current and direct current. 

6. Yes. It uses 220V supply and cell phone batteries are between 5V and 12V. 

7. When an emf is produced in a coil because of the change in current in a coupled coil , 

the effect is called mutual inductance. 

Vs 

Np 

= 

Vs 

Vp 

Ns 

= 

2000 

12 

240 


The Generator 




1. Show the principle behind the generation of electricity. 

2. Show energy transfer. 

3. Show a working electricity generator. 




the e hous 




the e hous 





Energy change Power Stations 

Generators 


Generation 


7,8,9 Technology Electricity & magnetism Power Stations 

Electricity ators gener 

Natural ience Sc Electricity Current ssociated a th wi 

magnetic eld 

Induction 

fi 


10,11,12 Physical Science Magnetism Magnetic fi eld / fl ux 

Electricity AC nd C a D ators gener 

Electrical Technology Electricity & Magnetism 

Power Station 

AC and DC generators 

Mechanical Technology Electricity AC and DC generators and 

alternators 

Questions 

Grade 1,2,3: 

1. Where can electricity come from? 

2. Is there electricity in a car? 


ME 21/11/12 V7

Questions 

Grade 4,5,6: 

3. What type of energy is found in the petrol in domestic generators? 

4. What is South Africa’s main source of generating electricity? 

Grade 7,8,9: 

5. What is a turbine? 

6. If you have a circuit with a coil connected to a galvanometer and have a magnet, in what two 

ways can you generate a current in the circuit? 

Grade 10,11,12: 

7. What type of mathematical graph will an alternating current generator produce? 

8. What is magnetic flux? 


1. William Beaty, 1996, Ultra-simple Electric Generator, Available at: [Accessed 23 August 2011]. 

2. Hans Peter, History of Electrostatic Generators, (Updated 30 October 2003) Available at: 


3. Wikipedia, 2011, Electric generator, (Updated 21 August 2011) 


4. Lazar Rozenblat, 2008, How an electric generator works, Available at: 



1. Sci-Bono exhibit: The generator. 

2. Sc-Bono exhibit: The magnet within the coil. 

3. Sci-Bono exhibit: The coil within the magnet. 

4. Sci-Bono exhibit: Spinning lights. 

5. Audio-Technica, December 2007, Product review, Available at: 


6. Bicycle lighting systems, November 2010, Dynamo powered lights, Available at: 


7. William Beaty, 1996, Ultra-simple Electric Generator, Available at: 



1. From power generating stations or batteries. 

2. Yes. From the battery and alternator. 

3. Chemical energy. 

4. Coal. 

5. A rotary engine that is able to extract energy from a moving fluid. 

6. Method one: moving the magnet in or over the coil. 

Method two: moving the coil over or in the magnet. 

7. Sinusoidal (sine graph). 

8. Magnetic flux is the amount of magnetic field that passes through a surface. 


Electric Fleas: 




1. Show the existence of charge. 

2. Show that opposite charges attract. 

3. Demonstrate how static electricity is produced. 

4. Show that charges can be transferred. 



1,2,3 Life Skills Safety in and Electricity and thunderstorms 


4,5,6 Life Orientation Safety in and Electricity and thunderstorms 


Natural Science Electricity Positive and negative charges 

in hunder a t torms 

Source or he f ectrical t el ircuit. c 

Technology Safety n ectricity i el Thunderstorms 

7,8,9 Technology Electricity Electrical ystem s n i a 

car park – s plug 

Safety n ectricity i el Thunderstorm 

Natural Science Electrostatics Positive and negative charges 

Thunderstorms 

10,11,12 Physical Science Electrostatics Positive and negative charges 

Thunderstorms 

Electricity High oltage v ystems s nd a 

spark . plugs 

Matter nd aterial 

ma Hydrosphere, mosphere At nd a 

Nitrogen ycle c 

Electrical Technology Electricity & Electronics Spark plugs 

Mechanical echnology T Electricity Spark plugs 


ME 21/11/12 V7

Questions 

Grade 1,2,3: 

1. Are the sparks of the electric fleas the same as that of the lightning of a thunderstorm? 

2. Is it safe to be inside a car or under a tree during a thunderstorm? 

Grade 4,5,6: 

3. What do the electric fleas demonstrate? 

4. Give examples of where sparks are found in everyday life. 

Grade 7,8,9: 

5. What charges are present during a thunderstorm? 

6. If the electric fleas are negatively charge, how did they obtain that charge? 

Grade 10,11,12: 

7. Will static electric charges collect on a copper wire? 

8. What instrument do you use to test for a charge? 


1. Yes. 

2. It is safe to be inside the car because the lightning strikes the outside area of the car and 

not the inside. If you stand under a tree the lightning will strike you. 

3. It demonstrates a spark between two points when there is a charge difference. 

4. Lightning from a thunderstorm and a welding spark. 

5. Positive and negative charges. 

6. The electric fleas received an excess of electrons form the material it was rubbed with. 

7. No. It is a conducting material and will cause the charge to flow and not collect. 

8. A gold leave electroscope. 

References and Interesting Websites Links 

1. Wikipedia, 2011, Static Electricity, (Updated 01 May 2011) Available at: [Accessed 02 May 2011]. 

2. Science Made Simple, 2009, Static Electricity Learn about static charge & static shock, 

Available at: [Accessed 02 May 2011]. 

3. California Energy Commission, 2011, Resistance and Static Electricity, Available at: [Accessed 02/05/2011]. 

4. Ron Kurtus, Basics of Static Electricity, (updated 23 January 2009) Available at: 

[Accessed 02/05/2011]. 

5. Exploratorium, Electrical Fleas, Available at: [Accessed 02/05/2011]. 



2. http://www.universetoday.com/81650/static-electricity/ 

3. http://www.electrostatics.com/page2.html 

4. http://instant-art.com/store/index.php?main_page=product_ 

info&cPath=1_84_87&products_id=7060 

5. http://www.experiland.com/html_projects/EM/11030202_EM_Build%20a%20Franklin%20 

bells%20device%20for%20detecting%20high%20voltage%20lightning%20storms.htm 


Luminglas 




1. Show an example of plasma. 

2. Demonstrate ionized gas molecules. 

3. Demonstrate the movement of ionized gas molecules in an electric fi eld. 

4. Show that the human body can alter electric fi elds. 



1,2,3 Life Skills Safety in and Electricity and thunderstorms 


4,5,6 Life Orientation Road Safety Electricity and thunderstorms 



in hunderstorm. a t 

Technology Safety n ectricity i el Thunderstorm 

7,8,9 Technology Electricity Electrical system in a car – 

spark plug 



Thunderstorms 


Thunderstorms 

Electricity Drawing lding & ircuits, bui c 

high voltage ystems s 

plug. 

nd park a s 





spark plug 

Mechanical Technology Electricity Circuits and spark plug 


ME 21/11/12 V7

Questions 

Grade 1,2,3: 

1. Are the electric flashes of the luminglas the same as that of lightning? 

2. What do you see when two live electricity wire touch? 

Grade 4,5,6: 

3. How many states of matter are there if we include plasma? 

4. Give examples of where electric sparks or arcs can be seen in daily life. 

Grade 7,8,9: 

5. What are the similarities between lightning and a luminglas? 

6. Give examples of phenomena that operate in the same way as the luminglas. 

Grade 10,11,12: 

7. What is plasma? 

8. Why does the discharge on the luminglas change when you put your hand on it? 

9. Why does a plasma TV screen not behave like the luminglas when it is touched? 


1. Wikipedia, 2011, Plasma, (Updated 28 July 2011), Available at [Accessed 02 August 2011]. 

2. Wikipedia, 2011, Plasma Globe, (Updated 16 June 2011), Available at: [Accessed 02 August 2011]. 

3. Wikipedia, 2011, Crackle Tube, (Updated 23 March 2011), Available at: [Accessed 02 August 2011]. 

4. Wikipedia, 2011, Plasma Display, (Updated 31 July 2011), Available at [Accessed 06 August 2011]. 



2. Wikipedia, 2011, Plasma Display, (Updated 31 July 2011), Available at [Accessed 06 August 2011]. 

3. Wikipedia, 2011, Plasma, (Updated 28 July 2011), Available at [Accessed 02 August 2011]. 


1. Yes. Is also has the same pattern. 

2. You will see a spark. 

3. Four. 

4. Lightning, a vehicle’s sparkplug, a static discharge. 

5. In both there is an electric discharge. 

6. Plasma TV, Spark plugs, globes, fluorescent lights, welding arc, etc. 

7. Plasma is a state of matterin which certain portions of the particles are ionized. 

It is similar to the gaseous state. 

8. The beams follow electric field lines. When you place your hand on the glass it alters the 

high-frequency electric field. This results in only one beam, which migrates to where 

you touch the glass. 

9. The electrodes of the plasma screen are distributed throughout the screen so touching the 

screen does not have much effect on distribution of the plasma. The luminglas has 

an electrode located at the centre of the luminglas with the plasma starting there and 

moving to the outer glass. 


Spark Plugs 




1. Show the working of a vehicle’s spark plugs and ignition system. 

2. Show the function of a distributor. 

3. Indicate a set fi ring order of an ignition system. 

4. Witness a spark from a spark gap. 



1,2,3 Life Skills Safety in and around Electricity and thunderstorms 

the e hous 

Static park s 

4,5,6 Life Orientation Safety in and Electricity and thunderstorms 

around the house Static spark 



Technology Safety n ectricity i el Thunderstorms 

7,8,9 Technology Electricity Electrical system in a car – 

spark plug 

Safety n ectricity i el Thunderstorms 


Thunderstorms 


Thunderstorms 


high voltage ystems s nd a 

spark plug. 

Matter and material Hydrosphere, Atmosphere and 



spark plug 



& esign D 

Questions 

Grade 1,2,3: 

1. If you have more batteries will you have more energy? 

2. How many electrical contacts or terminals does a battery have? 


ME 21/11/12 V7

Grade 4,5,6: 

3. What is the spark plug in the engine of a vehicle used for? 

4. If you touch an active spark plug, what will happen? 

Grade 7,8,9: 

5. What is the firing order in this exhibit? 

6. What is the energy source of the spark from the spark plug? 

Grade 10,11,12: 

7. What is a spark gap? 

8. What is the green cylinder unit in the exhibit and what is its function? 


1. Carlos Mano, The Functions of the Ignition Coil, 2010, Available at: 


2. Charles Ofria, 2006, A Short Course on Ignition Systems, Available at: 


3. Karin Nice, 2011, How Automobile Ignition Systems Work, Available at: 


4. Wikipedia, 2011, Spark Plug, (Updated 10 May 2011) Available at: 




2. Don Bowman, How to Change Spark Plugs, Available at 

[Accessed 30 July 2011]. 

3. Charles Ofria, 2006, A Short Course on Ignition Systems, Available at: 


4. Karin Nice, 2011, How Automobile Ignition Systems Work, Available at: 



1. Examples: lightning; welding; static spark; camera flash. 

2. Cars, trucks, buses, aeroplanes. 

3. To ignite the air-fuel mixture. 

4. You may injure yourself because it operates with high voltage and the spark may burn you. 

5. 1,3,4,2. 

6. The spark plug is connected in a circuit with vehicles battery, 

which is the source of the spark. 

7. A spark gap consists of an arrangement of two conductingelectrodes separated 

by a gap. The gas in the gap, usually air, must allow an electric spark to pass between 

these electrodes. 

8. It is called a coil. It is used to step up the voltage. 


Jacob’s Ladder 




1. Show an electric arc between two electrodes. 

2. Show the relationship between the electrode gap and arc. 



1,2,3 Life Skills Safety in and around Electricity and thunderstorms 

the ehous 

4,5,6 Life Orientation Safety in and around Electricity and thunderstorms 

the ehous 



Technology Safety n ectricity i el Thunderstorm 

7,8,9 Technology Electricity Spark , plugs rc elding a w 



Thunderstorms 


Thunderstorms 


high voltage ystems s nd a 

spark p. ga 





spark plug, rc elding a w 


Questions 

Grade 1,2,3: 

1. What must you do when you see a spark from an appliance? 

2. Is it safe to stand under a tree in a lightning storm? 

Grade 4,5,6: 

3. What type of precaution should you take when looking at a welding operation? 

4. Give an example of an electric arc in nature. 

Grade 7,8,9: 

5. Where do we use electric arcs? 

6. How is an ionized gas formed? 


ME 21/11/12 V7

Grade 10,11,12: 

7. Why is a high voltage required to produce an arc? 

8. What makes the arc move up the “ladder” in the exhibit? 


1. Wikipedia, 2011, Electric arc, (Updated 29 August 2011) 


2. Science Clarified, 2011, Electric arc, Available at: [Accessed 08 September 2011]. 

3. RH Fleet Science Center, 27 April 2009, Jocob’s ladder, Available at: [Accessed 08 September 2011]. 

4. SM Goldwasser, 2011, Jacob’s Ladder (Climbing Arc) Construction, Available at: [Accessed 08 September 2011]. 

5. Megan Shoop , 2011, How to Make an Electricity Arc Between Two Points, Available at: 

[Accesses 08 September 2011]. 



2. GAEC, 2009, Ionizing radiation, Available at: [Accessed 08 September 2011]. 

3. Usama Sardar, Electric World, Available at: 



1. Try to disconnect the power from the appliance and have it checked out. 

2. No. Lightning is attracted to trees. 

3. You should wear safety-welding glasses and stand some distance from the operation. 

4. Lightning. 

5. In lamps, furnaces, heaters, cutting torches, welding. 

6. If enough energy is supplied to the gas electrons can be dislodged from its atoms 

resulting in some molecules becoming positively charged and others negatively charged. 

7. A high voltage is required to ionize the gas. 

8. The ionized air around the arc becomes hot and rises. The arc therefore moves up. 


Sci-Bono Discovery Centre 

PO Box 61882, Marshalltown, 2107 

Corner President and Miriam Makeba Street 

Newtown, Johannesburg 

011 639 8400 

www.sci-bono.co.za 

Follow us on Twitter @scibono 

or join Facebook/scibono01 

118 Copyright Sci-Bono Discovery Centre 2011 2012 

ME 21/11/12 V7

Teaching Guide and References - Sci-Bono Discovery Centre

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