What electrical term is AC an abbreviation for?

AC is an abbreviation for alternating current, an electric current that periodically reverses direction and usually changes smoothly in magnitude over time.

Most household electricity is AC. Power stations generate it, and transformers can raise its voltage for efficient long-distance transmission or lower it for safer use in homes and businesses. This ability helped AC systems become central to modern electrical grids.

The standard waveform for utility AC is usually a sine wave. Its frequency is measured in hertz: many countries use 50 Hz, while others, including the United States, commonly use 60 Hz. By contrast, direct current (DC) flows in one direction, as in a battery-powered circuit.

A common mix-up is “AC” meaning air conditioning in everyday conversation. In an electrical or physics question, however, AC means alternating current. The term also applies beyond wall outlets: audio signals, radio carriers, and some motor systems are forms of alternating electrical behavior.