Electromotive force is a measure of the amount of work required to carry a unit of electric charge through a circuit. It is abbreviated as emf or E. The term also refers to the amount of energy obtained from an electric source per unit of charge passing through it. Such sources of electromotive force include batteries and electric generators. If 1 joule of electric potential energy is given to each coulomb of charge passing through the source, the emf of the source is 1 joule per coulomb, called 1 volt. See also Coulomb; Electric current; Joule; Volt.
