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Homework Help: Capacitor impedance from ExH

  1. Feb 20, 2010 #1
    1. The problem statement, all variables and given/known data
    A cylindrical capacitor(2 round plates with dielectric between them) with radius a, height hc and volume V.
    A sinusoidal voltage V0 is applied to the capacitor plates.
    Find the E-field inside the cap, Mag field Hs on the cap side wall(i.e at r=a)
    Use poynting theorem over the cylindrical surface to find power P provided to the cap.
    determine complex impedance Z of the cap, using the result of above.
    (ignore fringe fields)
    (crude fig. attached)

    2. Relevant equations

    3. The attempt at a solution

    I found the E field, which is (sigma/epsilon)

    H field at a is I/2(pi)a (using ampere's law)

    poynting theorem ExH, gave me (sigma/epsilon)*(I*hc)

    I have no idea how to get cap impedance from ExH result.

    Attached Files:

    • cap.jpg
      File size:
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    Last edited: Feb 20, 2010
  2. jcsd
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