Question

In a potentiometer arrangement for determining the emf of a cell, the balance point of the cell in open circuit is 350 cm. When a resistance of 9 Ω is used in the external circuit of the cell, the balance point shifts to 300 cm. Determine the internal resistance of the cell.

Answer 1

Internal resistance of the cell, `r = R(l_1/l_2 - 1) = 9(350/300 -1) = 1.5` Ω