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Ohm’s Law • Ohm’s Law states that the resistance of an object is constant and independent of the voltage across it....the potential difference across a load equals the product of the current through the load and the resistance of the load (limited to metal conductors at stable temperatures).
Ohm (Ω)- resistance of a device that allows current of 1 amp to flow when a potential difference of 1 volt is applied across the resistance. 1 Ω= 1Volt/Amp • Ohm’s Law means that the current in a circuit , kept at a constant temperature, is directly proportional to the voltage across a circuit and inversely proportional to the resistance of the circuit. Therefore, the greater the voltage, the greater the current and the greater the resistance, the lesser the current.
Since I = V/R, the current flowing through a circuit can be regulated in 2 ways: • 1. increase or decrease the voltage across the circuit (i.e. to get a stronger charge pump or use more batteries). • 2. increase or decrease the resistance of the circuit using devices called resistors. • If a device doesn’t obey Ohm’s Law, the graph of I versus V is non-linear (non-ohmic).
Do Sample Problem on Page 713 • Do Practice Problems on Page 714 #s 21 - 26