alternating current (AC)

A type of electrical current in which the electrical charge alternates between positive and negative. The rate of change between polarities is measured in Hertz (Hz), or cycles per second. Devices powered by alternating current include three electrical wires of different polarities: negative, positive, and neutral (or ground).

Conversely, direct current (DC) implements a two-wire circuit where the electrical charge travels in one direction. One wire is always negative and the other is positive.