Question

The specific resistance and cross-section area of potentiometer wire is $\rho$ and $A$ respectively. If a current $I$ is passed through the wire, the potential gradient of the wire will be :

• A. $\frac{I\rho }{A}$
• B. $\frac{I}{\rho A}$
• C. $\frac{IA}{\rho }$
• D. $IA\rho$

Answer 1

Answer: (A)

$\frac{I\rho }{A}$

Potential gradient $=$ potential difference per unit length.

So,$k=\frac{V}{l}=\frac{IR}{l}=\frac{I\left(\rho l/A\right)}{l}=\frac{I\rho }{A}$