Chapter 13 - Electric Circuits

Announcements Electrical Resistance Magnetic Fields Final QuestionsElectrical resistanceThe electrical resistance R of an object is a measure of how much an object impedes the flow of current (similarto friction)∆V = IRIn this equation, ∆V is the voltage drop across the resistor and I is the current through the resistorThe SI unit of electrical resistance is the volt-per-ampere, also called the ohm (Ω)Electrical resistance is a property of an object: it depends upon both the material and the shape of theobject (and other influences like the temperature)A conductor whose function in a circuit is to provide a specified resistance is called a resistorFor some materials R in this equation is constant (such devices are said to obey Ohm’s law)ResistorsThe rate at which energy is dissipated across a resistor is P = I 2 R = ∆V 2 /R, where I is the currentacross the resistor, R is the resistance of the resistor, and ∆V is the voltage drop across the resistorEnergy can not be created or destroyed, so where is this energy going?Electric Circuits