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Twisted Coil in a Magnetic Field

  1. Dec 28, 2008 #1
    The idea is as it follows:

    We have an homogeneus magnetic field that was increased from 0 to Bf. It induced a certain current (that accumulated to a charge Q) in a circular coil of radius a and resistivity [tex]\rho[/tex] constant. The question is, what would be the charge Q' when the coil is twisted (not strangled), forming an 8 of radii a1 and a2 in terms of Q?

    Thanks for your help
  2. jcsd
  3. Dec 29, 2008 #2


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    I don't see how charges could accumulate on a conducting coil due to an induced current.
  4. Dec 29, 2008 #3


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    The charge accumulated on a capacitor in series would be [tex]Q[a_1^2-a_2^2]/a^2[/tex].
  5. Dec 29, 2008 #4
    Nono, I expressed myself terribly. The idea is ALL the charge that circulated due to i is Q, I mean [tex]\int i·dt=Q[/tex]
  6. Dec 29, 2008 #5


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    Hmm it seems that in the latter case you can't just treat the 8-shape as two separate coils. For the current to flow in a particular direction in one of the the half-coil, it has to flow in the opposite circular direction. This complicates things somewhat.
  7. Feb 20, 2009 #6
    The charge is separated by the capacitor.

    Charge has to be conserved.
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