In a potentiometer experiment with the same source of constant e.m.f. (same driving cell) the following observations are made : For cell of e.m.f. 1.5 volts the null point is obtained at 1 meter from the common positive terminal. For another cell of e.m.f. E the null point is obtained at 2 meters from the same common positive terminal. Find the value of E. Neglect the internal resistance of the cells.

In a potentiometer experiment with the same source of constant e.m.f. (same driving cell) the following observations are made : For cell of e.m.f. 1.5 volts the null point is obtained at 1 meter from the common positive terminal. For another cell of e.m.f. E the null point is obtained at 2 meters from the same common positive terminal. Find the value of E. Neglect the internal resistance of the cells.