Question

Define the drift velocity of free electrons.

Answer 1

1. The drift velocity of free electrons is defined as the average velocity with which the free electrons get drifted towards the positive end of the conductor under the influence of an external electric field.
2. It is denoted by $V_d$
3. Drift velocity is related to an electric field as, $V_d$= - $eE\tau /m$ where $e$ is the electronic charge, $E$ is the electric field, and $\tau$ is the relaxation time.
4. Here negative sign indicates that drift velocity is opposite to the electric field i.e., the electron drifts from the lower potential to a higher potential.