Definition:Electromotive Force

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Electromotive force is a quantity that measures the source of potential energy in an electric circuit.

It is defined as the amount of work per unit electric charge.

It can be denoted $\EE$.


The usual symbol used to denote electromotive force is $\EE$.


The dimension of measurement of electromotive force is $\mathsf {M L}^2 \mathsf T^{-3} \mathsf I^{-1}$.

This derives from its definition as:

$\dfrac {\text{Work} } {\text {Charge} }$


The SI unit of electromotive force is the volt $\mathrm V$:

$1 \ \mathrm V = 1 \ \mathrm J \ \mathrm C^{-1}$

that is, $1$ joule per coulomb.

In the CGS unrationalised electromagnetic system, the base unit of electromotive force is the abvolt $\mathrm {abV}$.

In the CGS unrationalised electrostatic system, the base unit of electromotive force is the statvolt $\mathrm {statV}$.

Conversion Factors

\(\ds \) \(\) \(\ds 1\) volt
\(\ds \text {corresponds to}\) \(\) \(\ds 10^8\) abvolt (or e.m.u. of electric potential)
\(\ds \text {corresponds to (approximately)}\) \(\) \(\ds \dfrac 1 3 \times 10^{-2}\) statvolt (or e.s.u. of electric potential)

Also known as

Electromotive force can be abbreviated EMF, emf or e.m.f, and so on.

In common parlance, an electromotive force is referred to as voltage, from the fact that it is usually specified in volts.

Some sources also use this term, but this is deprecated on $\mathsf{Pr} \infty \mathsf{fWiki}$.

Also see