OHM’S LAW
ANALYSIS
Resistance is a measure of how much the component resists the flow of current. A
component with high resistance will not allow as much current to pass for a given
voltage as would a low valued resistor.
Ohmic Resistors
Resistors like the one you used in Steps 1-7 are “ohmic” in that they obey Ohm’s law:
V  IR
Ohm’s law states that voltage in a circuit is equal to the current through the circuit
multiplied by the resistance of the circuit (i.e. V varies linearly with I, and vice versa).
Non-Ohmic Resistance
All resistors, such as the light bulb in the challenge work, become non-Ohmic when
sufficiently hot. Your measurements should have shown that the bulb did not draw linear
current with voltage. In the case of the light bulb, the resistance changes as the light
bulb heats up more and more.
Resistors that heat up when current passes through them are commonly used tools in
our daily lives.
Property of LS&A Physics Department Demonstration Lab
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