Physics - Current Electricity Question with Solution | TestHub

Here AB is resistance wire having resistivity $\rho =\frac{8}{9\pi }{\mathrm{x}}^2$. If we close the key ${\mathrm{S}}_1$ and open ${\mathrm{S}}_2$, galvanometer shows null deflection. When we open key $S_1$ \& close key $S_2$, galvanometer again shows null deflection find the value of ${\epsilon }_0$ (in volt)