Electromotive force:- the emf of a source is defined as the work done by the source in taking a unit positive charge from its lower potential terminal to the higher potential terminal.

Or

It is the energy supplied by the source n taking a unit positive charge once round the complete circuit.

SI unit of emf is volt, it an electrochemical cell supplies energy of 1 joule for the flow of 1 coulomb of charge through the whole ckt, then its emf is said to be 1.

Difference between electromotive force and potential difference:

Electromotive force

Potential difference

  1. It is the energy supplied by the source in taking a unit positive charge once round the complete circuit.
  1. It is the work done in taking unit charge from one point of a circuit to other.
  1. It exist even when ckt is not closed.
  1. It exist even when ckt is closed.
  1. It is a cause.
  1. It is an effect.
  1. It is larger than the p.d. across any ckt element.
  1. It is always less than the emf.

 

Related Keywords
12    PMT    Physics    Current Electricity    E.M.F