Explain the term 'drift velocity' of electrons in a conductor. Hence obtain the expression for the current through a conductor in terms of 'drift velocity'.

Explanation

### Step-by-Step Solution

**Step 1: Define Drift Velocity**
Drift velocity (\(v_d\)) is defined as the average velocity that a free electron attains due to an electric field applied across a conductor. In the absence of an electric field, free electrons move randomly, resulting in a net displacement of zero. However, when an electric field is applied, these electrons experience a force that causes them to drift in the direction opposite to the electric field.

**Step 2: Explain the Effect of Electric Field**
When a potential difference is applied across the ends of a conductor, an electric field (\(E\)) is established, given by:
\[
...