Question

42.
In a potentiometer experiment, a cell balances
against a length of 350 cm of the
potentiometer wire when it is shunted by a
resistance of 40 ohm The balancing length
reduces to 280 cm when it is shunted by a
resistance of 15 ohm Find the internal resistance
of the cell.
(A) 7.06 ohm
(B) 16.8 ohm
(C) 17.10 ohm
(D) 18.6 ohm​

Answer 1

complete solution in attached photos , so option (a) correct.