Question

8. 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 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

The balance point fo the cell in ofen circuit , l1 = 350cm

After applying resistance, balance point l2 = 300cm

Resistance in internal circuit = 9 Ω

Internal resistance can be calculated by relation below:

r = (l1/l2 - 1) x R

r = (350/300 - 1) x 9

r = 50/300 x 9 = 3/2 = 1.5 Ω

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