• Electric Potential & EMF

Electric Potential and Electromotive Force

Electric Potential

Moving a charge from one point to another requires an expenditure of energy. Electric potential is the amount of work needed to move a unit of charge.

The potential difference in a voltage source (battery).

A change in electric potential between two specific points in an electrical element or electric circuit is called a potential difference or voltage. It is the measure of the work required to move charge through it. The more energy electrons have, the stronger the potential difference. For a continuous current to flow between two points in a circuit, voltage is required between them. The unit of potential difference is volt (symbol: V) named after Alessandro Volta.

Since one volt is the work required to move a unit of charge, then:

$$ \mathbf{V=\frac{W}{Q}} $$ $$ \begin{align} \mathbf{V} & - \text{ voltage, Volt (V)} \\ \mathbf{W} & - \text{ work, Joule (J)} \\ \mathbf{Q} & - \text{ charge, Coulomb (C)} \\ \end{align} $$

Electromotive Force (E. M. F.)

The electromotive force in a voltage source (battery).

Electromotive force is the maximum potential difference when there is no electric current or when it not connected to an electric circuit. It is provided by a source of energy such as a battery or a generator. It is independent of any elements in an electric circuit. It is have the same unit as the potential difference: volt.