Physics - Current Electricity Question with Solution | TestHub

The circuit consists of two identical resistors with resistance R and two identical nonlinear elements, whose voltage - current relationship looks like $\mathrm{U}=\alpha {\mathrm{I}}^2$, where $\alpha =2\frac{\text{ volt }}{{\text{ Ampere }}^2}$. At which emf $\mathcal{E}$ of the source the current through the galvanometer is equal to zero? Resistance of the source can be neglected. $\mathrm{R}=3\Omega$.