Using the results of the above example on Example 20.3, find the drift velocity in a copper wire of twice the diameter and carrying 20.0 A.
Example 20.3: Calculating Drift Velocity in a Common Wire Calculate the drift velocity of electrons in a 12-gauge copper wire (which has a diameter of 2.053 mm) carrying a 20.0-A current, given that there is one free electron per copper atom. (Household wiring often contains 12-gauge copper wire, and the maximum current allowed in such wire is usually 20 A.) The density of copper is 8.80 × 103 kg/m3 .
The value of drift velocity in copper wire is -1.132 x 10-4 m/s
The negative sign indicates that the negative charge is moving in the direction opposite to conventional current.