Question
Sun July 24, 2011 By: Hardik Gupta

What actually is emf and what is that makes emf differ from potential difference?

Expert Reply
Sun July 24, 2011
EMF or electro motive force is measured by the amount of work done in moving a unit positive charge in the complete circuit inside and outside the cell but potential difference is the amount of work done in moving a unit positive charge in the circuit outside the cell.
EMF is a characteristic of the cell i.e., it does not depend on the amount of current drawn from the cell but potential difference depends on the amount of current drawn from the cell. More the current is drawn from the cell, less is the potential difference.
EMF is equal to the potential difference when cell is not in use, while greater than the terminal voltage when cell is in use whereas potential difference is equal to the emf when the cell is not in use and less than the emf when the cell is in use. 
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