Ncert Exercises & Solutions

Which of the following characteristics of electrons determines the current in a conductor?

1. Drift velocity alone

2. Thermal velocity alone

3. Both drift velocity and thermal velocity

4. Neither drift nor thermal velocity

(a) Hint: The electrons do random motion due to their thermal energy.

Step 1:

The relationship between current and drift speed is given by:

$I = {neAv}_{d}$

Here, I is current and $v_{d}$ is the drift velocity.

Step 2:

So $I \propto$ $v_{d}$

Thus, only drift velocity determines the current in a conductor.