Potentiometer
Two cells of e.m.f.s and are connected as shown in figure.

When the potentiometer is connected between A and B, the balancing length of the potentiometer wire is 3.60 m. On connecting the potentiometer between A and C, the balancing length is 0.90 m. The ratio is
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Answer:
- A–C gives a smaller length, so the cells oppose there.
- A–B: ; A–C: .
- , so .
- So the answer is (b) .