Ch. 19-2

The opposition to the motion of charge in a conductor.

For most metals, resistance is constant over a wide range of applied potential differences.

I = amperes (A) V = volts (V) R = ohms (Ω)

Resistance depends on:

• Length

• Cross sectional area

• temperature

• Material

Sample Problem 19B pg. 702

Material that has zero resistance below a certain critical temperature.

19-3

Rate at which charge carriers do work.

P = Watts (W)

I = Amperes (A)

V = Volts (V)

Power companies charge for energy in kilowatt-hours (kWh)

Sample Problem 19D pg. 712