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Homework Help: Magnetic field inside capacitor - is this right?

  1. Nov 18, 2008 #1
    1. The problem statement, all variables and given/known data
    A 10 cm diameter parallel plate capacitor has a 1 mm spacing. The electric field between the plates is increasing at the rate of 1.0 * 10 ^6 V/ms. What is the magnetic field strength (a) on the axis (b) 3.0 cm from the axis

    2. Relevant equations

    3. The attempt at a solution
    dE/dt = 1.0 e6
    displacement current = dFlux/dt * permittivity constant = dE/dt * A * 8.85e-12
    displacement current = 1.0e6 * pi * .05^2 * 8.85e-12 = 6.95e-8

    The first part of the Ampere Maxwell equation falls out, leaving
    B*s = displacement current

    For on axis s= 0 , so is the magnetic field infinite?

    B*2pi*.03 = 6.95e-8 B = 3.688 e-7 T

    Is this correct?
  2. jcsd
  3. Nov 18, 2008 #2
    actually I messed the problem up here. I got it now.
    Last edited: Nov 18, 2008
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