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Homework Help: Magnetism/magnetic field

  1. Oct 12, 2004 #1
    a long, straight wire carries a current of 52 A. The magnetic field produced by this current at a certain point is 9.0 x 10^-5 T. How far is the point from the wire?

    i figured i should be using the equation

    F = I L B sin 90

    but i can't find the force. any help?
  2. jcsd
  3. Oct 13, 2004 #2


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    You need to use Ampere's law to find the field. It's cylindrically symmetric about the wire. The magnetic field will be azimuthal about the wire so the integration is easy to do (integrate around a circle).
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