Question

A potential difference $V$ is applied to a copper wire of length $l$ and radius $r$. If $V$ is doubled, the drift velocity

• A. is doubled
• B. is halved
• C. remains same
• D. becomes zero

Answer 1

The correct option is A is doubled

We know that drift velocity is given by

$v_d=\frac{eE}{m}\tau =\frac{eV}{ml}\tau$

Where,
$m\to$ mass of charge
$E\to$ applied electric field across wire

Assuming all are constant except $V$

$\therefore v_d\propto V$

If $V$ is doubled, $v_d$ also doubled.

Hence, $\left(a\right)$ is correct.