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Homework Help: Simple Capacitance help

  1. Jul 18, 2010 #1
    1. The problem statement, all variables and given/known data

    The capacitance of a water-filled parallel-plate capacitor with plate area 3.0×10^−3m^2 and separation 4.0×10^−2 mm is
    0.66 uF
    1.3 nF
    53 nF
    660 nF


    2. Relevant equations

    C=E_0A/d

    3. The attempt at a solution
    C=8.85*10^-12*3*10^-3/4*10^-5
    C=6.64*10^-10
    This is none of the options. I think that the constant 8.85*10^-12 may be wrong since the capacitor is water not air???
     
  2. jcsd
  3. Jul 18, 2010 #2

    rl.bhat

    User Avatar
    Homework Helper

    Re: Capacitance

    C = KεοA/d where K is the dielectric constant of water. Find its value in Wikipedia. Answer is 53 nF.
     
  4. Jul 18, 2010 #3
    Re: Capacitance

    thanks a lot for that.
     
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