com www.GOALias.blogspot.com www.GOALias ... - fun learning

www.GOALias.blogspot.comFig. 14.12 Glowing filament of an electric bulbafter connecting to the electric supply,their elements become red hot and giveout heat.The amount of heat produced in awire depends on its material, lengthand thickness. Thus, for differentrequirements, the wires of differentmaterials and different lengths andthicknesses are used.The wires used for making electriccircuits do not normally become hot. Onthe other hand, the elements of someelectric appliances become so hot thatthey are easily visible. The filament ofan electric bulb gets heated to such ahigh temperature that it starts glowing.If a large current passes through awire the wire may become so hot that itmay even melt and break. But is itpossible for a wire to melt and break?Let us check it out.Activity 14.4Make the circuit we used for Activity 14.3again. However, replace the cell with abattery of four cells. Also, in place ofAn electric bulb is used for light but it also gives heat. This is not desirable. Thisresults in the wastage of electricity. This wastage can be reduced by usingfluorescent tube lights in place of the bulbs. Compact fluorescent lamps (CFLs)also reduce wastage and can be fixed in the ordinary bulb holders.Fig. 14.13 Tube lights and CFLsHowever, before buying bulbs or tubes, or CFLs, look for the ISI mark of theBureau of Indian Standards. In fact, before buying any electrical appliance,look for this mark. The ISI mark ensures that the appliance is safe and wastageof energy is minimum.165ELECTRICCURRENTAND ITS EFFECTS165