alternating current

noun

1. an electric current that reverses direction at regular intervals, having a magnitude that varies continuously in sinusoidal manner. : ac

alternating current

noun

1. a continuous electric current that periodically reverses direction, usually sinusoidally AC Comparedirect current

alternating current

/ ôl′tər-nā′tĭng /

1. An electric current that repeatedly changes its direction or strength, usually at a certain frequency or range of frequencies. The term is also used to describe alternating voltages. Power stations generate alternating current because it is easy to raise and lower the voltage of such current using transformers; thus the voltage can be raised very high for transmission (high voltages lose less power as heat than do low voltages), and lowered to safe levels for domestic and industrial use. In North America, the frequency of alternation of the direction of flow is 60 Hz, or 60 cycles per second. In other parts of the world it is 50 Hz.
2. Compare direct currentSee Notes at current

alternating current

1. An electric current (see also current ) in which the flow reverses periodically. ( Compare direct current (DC) .)

Notes

In the United States, most household current is AC, going through sixty reversal cycles each second. Electric motors in household appliances are designed to work with current at this rate of reversal.

Word History and Origins

Origin of alternating current¹

First recorded in 1830–40

Example Sentences

The principal difference between the continuous-and alternating-current dynamo, is in the number of magnets used.

From Project Gutenberg

I am supposing that our plant consists of an alternating-current dynamo with a small exciter.

From Project Gutenberg

The study of the alternating-current arc has suggested a number of new experimental problems for investigators.

From Project Gutenberg

The periodic variation of light in the alternating-current arc has also been the subject of inquiry.

From Project Gutenberg

By this method the variations of electric quantities in an alternating-current arc can be watched.

From Project Gutenberg