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Homework Help: Order of magnitude of the magnetic force

  1. Apr 19, 2005 #1
    A proton of mass 1.7 x 10^-27 kg and spped 3 x 10^7 meters per second is moving in a circle of a radius of 200 meters.

    What formula do I need to use to find out the best estimate of the order of magnitude of the magnetic force needed to maintain this motion?
  2. jcsd
  3. Apr 19, 2005 #2
    The lorentz force.

    F=q(E+v x B)
  4. Apr 19, 2005 #3
    Any time something is traveling in a circle, it must be because of a centripedal force. In this case, the centripedal force is the lorentz force:

    qvB = (mv^2)/r
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