1. The pressure that causes electrons to move in an electrical circuit, measured as the amount of energy supplied by an electric current passing through a given source, as measured in volts.
2. The electric potential, or ability of electric energy to perform work.

Electromotive force is usually measured in joules per coulomb, or volts; and the higher the voltage, the greater the potential of electric energy.

Any device; such as, a storage battery, that converts some form of energy into electricity is a source of electromotive force or EMF or emf; or, a generator produces an electromotive force.

3. The difference in electric potential, or voltage, between the terminals of a source of electricity; such as, a battery from which no current is being drawn. When current is drawn, the potential difference drops below the emf value.
4. The force that causes a flow or the movement of electrons through an electrical circuit.

It is the amount of energy derived from an electric source in one second when one unit of current is passing through the source, commonly measured in volts.

Electromotive force is produced by differences in electrical charge or potential.

5. Energy per unit electric charge that is imparted by an energy source; such as, an electric generator or a battery.

When the device does work on the electric charge being transferred within itself, energy is converted from one form to another.

A list of elements arranged according to their standard electrode potentials, with noble metals; such as, gold, being positive and active metals, including zinc, being negative.