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AC current

  1. Apr 27, 2013 #1
    what does the positive and negative half cycles in an ac represent?
  2. jcsd
  3. Apr 27, 2013 #2


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    Gold Member

    The direction of the current. That's why it's called ALTERNATING current.
  4. Apr 27, 2013 #3
    What does the C in AC stand for?
  5. Apr 27, 2013 #4

    jim hardy

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    I gather you're referring to a waveform?
    It's a graph of volts versus time.
    Traditionally horizontal axis is time; vertical is voltage with positive up and negative down.
  6. Apr 28, 2013 #5
    Personally I never liked the "C" - because power requires voltage AND current. In AC BOTH the voltage and current change polarity - so (typically) the power is always flowing in one direction.
  7. Sep 19, 2016 #6
    Positive and negative cycles represent the direction of the alternating current.AC reverses its direction many times in a second.Number of times it changes its direction in a second is measured as frequency.Go through the Alternating current for more information..
  8. Sep 19, 2016 #7


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    Staff: Mentor

    Except for the special case of the load being purely resistive, the power in AC does alternate with each positive pulse followed by a smaller negative pulse to deliver an average power that is positive.
  9. Sep 19, 2016 #8


    Staff: Mentor

    Sorry, but no. The positive and negative half cycles are the same size and there is no pulsing. When V and I are in-phase, V*I is positive when both V and I are positive, and V*I is positive when V and I are both negative. Look at the drawings in the Insight article.
  10. Sep 19, 2016 #9


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    Staff: Mentor

    Maybe you didn't understand what I wrote?

    That's a useful article, including this figure which neatly illustrates the general case I describe:

    Last edited: Sep 19, 2016
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