Drift velocity is the average velocity that a charge carrier, such as an electron, attains due to an electric field. In a copper wire carrying current, these charge carriers are predominantly free electrons. The flow of electricity in the wire can be thought of as these electrons drifting through the metallic structure of the wire. Although individual electrons move at tremendous speeds randomly, their average net motion is slow and their drift velocity can be calculated using the formula:where:
- is the current through the wire, which is given as 5.00 A.
- represents the number density of electrons, for copper it is given as electrons per cubic meter.
- is the cross-sectional area of the wire.
- is the charge of an electron, which is coulombs.
Substituting these values calculates how fast electrons drift through the wire, highlighting that the motion responsible for electric current is far slower than one might assume.