Question

For a potentiometer, why should the emf of the auxiliary battery be greater than the emf of the cell to be measured?

Answer 1

The e.m.f. or electromotive force of the auxiliary battery should be slightly greater than the electromotive force of the individual cells because null point will not be obtained on the potentiomenter wire if the battery has lesser e.m.f.

A potentiometer is an instrument used to measure the potential difference or electromotive force of a cell. It works on the principle that for a constant current, fall of potential along a uniform wire is directly proportional to its length.