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Homework Help: Parallel plate capacitor and insulating material

  1. May 22, 2009 #1
    1. The problem statement, all variables and given/known data

    A parallel-plate capacitor has plates of 10 cm^2 area separated by a 0.10mm layer of glass insulation with resistivity rho = 1.2x10^13 omega*m and dielectric constant k= 5.6. Because of the finite resistivity, current can leak through the insulation.

    How do I Show that it depends only on the properties of the insulating material and not on its dimensions?

    2. Relevant equations

    C= emf(A/d)

    3. The attempt at a solution
    I found the time constant for this capacitor to discharge through its insulation. T= 590s
  2. jcsd
  3. May 22, 2009 #2


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    Homework Helper

    Consider the resistivity


    Consider too the equation you have for capacitance.

    Notice anything about how - when you combine the 2 - the RC has a tendancy not to be dependent on the cross sectional area?
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