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Whats reverse electromagnetic force?

  1. Jun 12, 2007 #1
    hi

    can you please tell me what is reverse electromagnetic force?

    thankz!
     
  2. jcsd
  3. Jun 12, 2007 #2

    berkeman

    User Avatar

    Staff: Mentor

    I believe that you are referring to "back EMF" that is generated in a coil or transformer.

    http://en.wikipedia.org/wiki/Transformer

    When you put an AC voltage across the primary of a transformer, that generates an AC (lagging) current in the primary. That AC current generates an AC magnetic flux, which couples to the secondary coil. That changing flux induces a current in the secondary coil, which generates its own flux in the core, and that secondary flux opposes the primary flux. So any current flowing in the secondary causes a reduction of input impedance in the primary (the so-called Back EMF, or reverse voltage due to the reflected load impedance).

    Does that help?
     
  4. Jun 13, 2007 #3
    ya that helps!!
    thankz!
     
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