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Homework Help: Induced Currents and Magnetic Fields

  1. Dec 2, 2007 #1
    1. The problem statement, all variables and given/known data

    The north end of a bar magnet is pushed downward toward a wire loop in the plane of the paper. In which direction is the induced current, and which way is the induced magnetic field?

    A. clockwise, into the paper
    B. clockwise, out of the paper
    C. counter-clockwise, into the paper
    D. counter-clockwise, out of the paper
    E. There is no induced current.

    2. Relevant equations

    I found a statement in the book that says the direction of an induced current is always opposes the change in magnetic flux that induces the current.

    Edit: I just found a statement that says:

    The direction of the magnetic field is perpendicular to the wire and is in the curling direction of your right hand fingers. The direction of your thumb is the direction of electric current.

    3. The attempt at a solution

    The answer key states the answer is D. However, the key is not always correct.

    Direction problems always get me confused. If anybody could explain this problem to me perhaps I could get a better idea of what is going on here. Thanks in advance!
    Last edited: Dec 2, 2007
  2. jcsd
  3. Dec 2, 2007 #2


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    Science Advisor
    Gold Member

    First you need to determine the direction of the induced current in the loop (What does your text say about inducing a current with a changing magnetic field?). Then use your right hand thumb rule.
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