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alternating current

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

First recorded in 1830–40
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for alternating current

Historical Examples of alternating current

  • I will now explain the nature of an alternating-current dynamo.

    Wrinkles in Electric Lighting

    Vincent Stephen

  • The alternating-current arc-lamp was developed after the appearance of the direct-current open-arc and has been widely used.

    Artificial Light

    M. Luckiesh

  • In alternating-current circuits its place is taken by the dynamometer type, which reads both direct and alternating currents.

  • The second torpedo they caught and deflected on a beam of alternating-current magnetism that repelled it.

    The Ultimate Weapon

    John Wood Campbell

  • Its two fundamental parts are an alternating-current generator and a polarized bell-ringing device.


British Dictionary definitions for alternating current

alternating current

noun
  1. a continuous electric current that periodically reverses direction, usually sinusoidallyAbbreviation: AC Compare: direct current
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

alternating current in Science

alternating current

[ôltər-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. Compare direct current. See Notes at current Tesla.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

alternating current in Culture

alternating current

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

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Note

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.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.