Question

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

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

Answer 1

The correct option is C remains same

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

From above expression we can clearly see that drift velocity does not depend upon radius.

Hence, drift velocity remains constant.