Question

define
electromotive force of a cell.

Answer 1

AnswEr:

Electromotive force :

It is defined as the difference in potential between two terminals of a cell when key k is off i.e no current is being drawn form the cell in external circuit i.e when circuit is open. EMF is misnomer since by name it seem that it is a force but actually it work done per unit charge. Its unit as per by name is dyne or Newton but actually its unit is volt.

Always Potential difference < Electromotive force except in one case. That case is of charging the cell. During charging potential difference > Electromotive force.

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