Question

The current in a copper wire is increased by increasing the potential difference between its ends. Which one of the following statements regarding $n$, the number of charge carriers per unit volume in the wire and $v_{d}$, the drift velocity of the charge carriers is correct?

• A. $n$ is unaltered but $v_{d}$ is decreased
• B. $n$ is unaltered but $v_{d}$ is increased
• C. $n$ is increased but $v_{d}$ is decreased
• D. $n$ is increased but $v_{d}$ is unaltered

Answer 1

Answer: (B)

$n$ the number density, depends on the atomic structure of the material.
$\frac{V}{R}=I=n e A \cdot v_{d}$
As $V$ increases, $I$ increases, $v_{d}$ increases.