Question

A potentiometer wire is $5m$ long and a potential difference of $6V$ is maintained between its ends. Find the emf of a cell which balances against a length of $180cm$ of the potentiometer wire.

Answer 1

In a potentimeter wire, voltage is linearly spread over the entire length of wire, which is characteristic of any resistor.

Hence, we have: $\frac{X}{V^{\prime }}=\frac{L_0}{V_0}$

$⟹V^{\prime }=\frac{X}{L_0}{V}_0$ $=\frac{1.8}{5}\times 6V$ $=2.16V=$ EMF of the cell