2014-09-23T09:46:46+05:30 done by the electric force on unit positive charge to move it through a distance 'l' from A toB is called potential difference between those points. 2.the s.I unit of potential difference is volt 3.potential difference can be measured by using voltmeter which is connected parallel in a circuit.
Potential difference is the work done in bringing the unit positive charge from infinity to the vicinity of similar positive charge

When circuits are closed then the potential difference across the ends of terminal of cell is known as emf