Potential difference between two points f (final) and i (initial) is defined to be equal to the amount of
work done (by external agent) in moving a unit positive charge from point i (initial) to f (final)
Vf - Vi = (Wif /q)
If work done in carrying a unit positive charge from point 1 to point 2 is one joule then the potential
difference V2 – V1 is said to be one volt. Potential difference may be positive or negative.
The work done against electrical forces in transporting a charge q from point i (potential Vi) to point f (potential Vf) is W = qV where V = Vf – Vi.
