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Torque on a charged particle moving in a circle in a uniform B field

  1. Mar 6, 2009 #1
    1. The problem statement, all variables and given/known data

    A particle of charge q = e moves in a circle of radius = 0.44 m with speed v = 2.350×107 m/s. Treating the circular path as a current loop with constant current equal to its average current, find the maximum torque exerted on the loop by a uniform magnetic field of magnitude B = 1.00 T.

    2. Relevant equations


    3. The attempt at a solution

    I'm stuck and I don't really know where to go. I did find the mass by the following equation:
    m = rqB / v
    m = 0.44 * 1.602E-19 * 1 / 2.35E7
    m = 2.999E-27 kg

    I could also find KE but I'm not sure what to do with either of these two. How does torque relate to magnetism?
  2. jcsd
  3. Mar 6, 2009 #2

    Doc Al

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    Staff: Mentor

    You are solving a different problem. Realize that the given magnetic field is not the field that is making the charge go in a circle.

    Treat the moving charge as a current loop. (What's the average current?) A current loop placed in a magnetic field will experience a torque. Look up: torque on a current loop, magnetic moment of a current loop.
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