A galvanometer has a current sensitivity of 1 mA per division. A variable shunt is connected across the galvanometer and the combination is put in series with a resistance of 500 Ohm and a cell of internal resistance 1 Ohm. It gives a deflection of 5 division for shunt of 5 Ohm and 20 division for shunt of 25 Ohm. The emf of cell is
