Question

Explain with neat circuit diagram how will you determine unknown resistance by using meterbridge experiment.

Answer 1

The key $K_1$ is closed to pass a current by choosing a suitable resistance R in the resistance box. The jockey is tapped along the wire to locate the null point i.e., galvanometer shows no deflection. The bridge is then said to be balanced.
By principle of wheatstone's bridge.
$\frac{R}{S}=\frac{l_1}{100-l_1}$
So, $S=\frac{(100-l_1)\times R}{l_1}$
As $R$ is known values so unknown resistance $S$ can be calculated.