Q 12-03-038NEETJEE MainMedium
The emfs of two cells are compared with a potentiometer. The balancing lengths are $300$ cm and $200$ cm when used singly, and the cells are then connected in series so as to aid each other. The balancing length for the combination is
Answer: (C) $500$ cm
$E \propto l$, so aiding emfs add: $300 + 200 = 500$ cm.
Solution by Sreeraj P, M.Sc Physics