A current of 1.0 mA is flowing through a potentiometer wire of length 4 m and of resistance 40 N. The potential gradient of the potentiometer wire will be:

$10^{-2} V/m$

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

The potential difference across the wire can be calculated using ohm's law -

$V=I×R$ [By Ohm's law]

$=(1×10^{-3})×40=0.04V$

∴ Potential gradient = $\frac{V}{L}=\frac{0.04}{4}=10^{-2}V/m$