When a cell is connected in the secondary circuit of a potentiometer, the balance length is found to be 810 cm. When the cell is shunted with a 5 Ω resistor, the balance length is found to be reduced to 675 cm. The internal resistance of the cell is
1 Ω
Internal resistance of the cell, r=R[I1−I2l2]
Where l1=810 cm Balancing length when no current flows through ‘R’
l2 =675 cm Balancing length when current flows through ‘R’