PHYS345 Electricity and Electronics

Ohm's Law and Resistance

Simple circuit experiment -- with better quality graph

Definition of Resistance
If a material obeys the relationship above, over a wide range of voltages, it is said to be ohmic. Not all devices are ohmic, and fortuately so, or we would not have the wonderful semiconductor-based devices to which we have become so accustomed. However over the next few classes we will be considering resistors to be made from ohmic materials.

The unit of resistance is volt/amp, known as an ohm, and represented by upper case omega.

Units of Resistance
Symbol for ohms

Resistance controls the amount of current that results when voltage difference is applied to a resistor.

Ohm's Law
Ohm's Law

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Last updated Sept. 2, 1998.
Copyright George Watson, Univ. of Delaware, 1998.