Current Electricity

In potentiometer experiments, two cells of e. m. f. '\(E_1\)' and '\(E_2\)' are connected in series \(\left(E_1>E_2\right)\), the balancing length is \(64 \mathrm{~cm}\) of the wire. If the polarity of \(E_2\) is reversed, the balancing length becomes \(32 \mathrm{~cm}\). The ratio \(\mathrm{E}_1 / \mathrm{E}_2\) is