Voltage is a difference in electrical potential. Although voltage is sometimes referred to as the electromotive force, voltage is actually a potential difference. Usually voltage is expressed in volts (V), a unit of electrical measurement named after Italian physicist Alessandro Volta.

Voltage refers to the difference in electrical potential between two points, not the electrical potential itself. The difference in electrical potential between two points A and B is defined as the change in potential energy divided by the charge moved. The change in potential energy can be thought of as the negative of the work done to move a charge in an electric field. When a charge q moves in an electric field E from point A to point B, the work done on the charge by the electric field is qEd, where d is the distance between points A and B. In this case, the change...