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Difference in the maximum potential capacitance

  1. Jun 30, 2009 #1
    Determine (a) capacitance and (b) the difference in the maximum potential that can be applied to a parallel plate capacitor filled with Teflon (k=2,1), whose area the plate is 1,75 cm^2 and the separation between the plates is 40x10^{-6}m.


    My solution

    (a) C. = ( E. * A )/d = 3,87x10^{-12}F
    C = k * C. = 8,127x10^{-12}F

    (b) not understand
     
  2. jcsd
  3. Jun 30, 2009 #2

    LowlyPion

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  4. Jun 30, 2009 #3
  5. Jun 30, 2009 #4

    LowlyPion

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    Re: capacitance

    You don't need Q.

    The dielectric strength is only dependent on distance, and that you are given.
     
  6. Jun 30, 2009 #5
    Re: capacitance

    I do not know the formula. But what you are saying is that:
    V / (Dielectric strength) = separation between plates ?
     
  7. Jun 30, 2009 #6

    ideasrule

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    Re: capacitance

    Yes! V=Ed, or V/E=d, for uniform E.
     
  8. Jun 30, 2009 #7
    Re: capacitance

    But I do not have E
     
    Last edited: Jun 30, 2009
  9. Jun 30, 2009 #8

    ideasrule

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    Re: capacitance

    What are the units for dielectric strength?
     
  10. Jun 30, 2009 #9
    Re: capacitance

    In this problem I have the dielectric constant (no unit). I do not have the dielectric strength
     
  11. Jun 30, 2009 #10

    LowlyPion

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    Re: capacitance

    The link I gave you earlier has a number for the dielectric strength.

    http://en.wikipedia.org/wiki/Dielectric_strength

    You know the thickness, so figure the maximum voltage.
     
  12. Jun 30, 2009 #11
    Re: capacitance

    Dielectric Strength = 1,73x10^8

    V = 1,73x10^8 * 40x10^{-6} = 6920 V


    which symbol to Dielectric strength ?
     
  13. Jun 30, 2009 #12

    LowlyPion

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    Re: capacitance

    Whatever strikes your fancy.
     
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