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A Question on transformers

  1. Nov 16, 2014 #1
    So I was just reading on generators. The basics that I've understood is that it works by inducing a current through motion of a coil on a magnetic field.
    So what I didn't understand was that it produces an alternate current through full 360` rotation. In a half cycle, it induces a current in one direction and in the other half cycle it induces the current in the opposite direction. What I don't understand is that if it is rotating ONLY clockwise or anticlockwise, then why is it producing an alternating current? I thought that would happen if it rotated a half-cycle clockwise and then it rotated back to its original position by rotating a half cycle anticlockwise.
    Also on a side note, doesn't the wire get twisted up if the coil keeps rotating in one direction constantly?

    Edit: The title says transformers while I meant generators.
    Last edited: Nov 16, 2014
  2. jcsd
  3. Nov 16, 2014 #2


    Staff: Mentor

    I think your question is about AC generators. Transformers don't rotate in most circumstances.

    Just like any other circular motion, a coil rotated by 360 degrees is back where it started from. Rotate it agai I. The same direction and it will be back in the same place once again. You don't need to know anything about electricity to see that.
  4. Nov 16, 2014 #3
    Oh right I'm so sorry, I mistakenly wrote transformers when I wanted to write generators.
  5. Nov 16, 2014 #4
    Yeah but why doesn't it make an AC current. If it's rotating in one direction, then won't it just create a DC?
  6. Nov 16, 2014 #5


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    It would be a good idea to Google AC generator because there are dozens of diagrams and even animations to see.
    First of all, the wires don't get twisted because Slip Rings and Brushes are used.
    Secondly, as the coil rotates, the wires go up and down through the field, that changes the direction of the current, whichever direction the coil rotates. If you want DC out, you have to do complicated switching to keep the current in the same direction all the time. (A Commutator) Look at those diagrams - google 'Animations AC generator' and watch the pretty pictures.
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