The resistivity of a potentiometer wire is $10^{-7} \Omega m$ and its cross-section area is $10^{-6} m^2$. When a current of 0.1 A flows through the wire, its potential gradient is:

$10^{-2} V/m$

The correct answer is Option (2) → $10^{-2} V/m$

Resistance (R) of the wire is -

$R=ρ\frac{L}{A}=10^{-7}×\frac{L}{10^{-6}}=0.1L$

$V=IR$ [By Ohm's law]

$V=0.1L×0.1$

$⇒\frac{V}{L}=0.01V/m$