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Homework Help: Potential difference across capacitors, can someone check this?

  1. Nov 1, 2007 #1
    1. The problem statement, all variables and given/known data
    What is the potential difference across C2 when C1 = 5.0 µF, C2 = 15 µF, C3 = 30 µF, and V0 = 24 V?
    http://img503.imageshack.us/img503/9994/capacitanceqb1.jpg [Broken]


    2. Relevant equations

    C = Q/V


    3. The attempt at a solution

    I calculated total capacitance of C1 and C3 in parallel, that is 3.5 x 10^-5 Farads.

    So the charge going across is Q = CV = 3.5x10^-5 x 24 = 8.4 x 10^-4 C

    Therefore the voltage going across the other capacitor is V = Q/C, which 8.4x10^-4/15x10^-6 = 56V

    Which looks really wrong.

    Help?

    Thanks in advance.
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Nov 1, 2007 #2
    Wait I redid it. I first calculated the total capacitance which turned out to be 1.5x10^-5 Farads.

    Got the total charge by Q = CV, 1.5x10^-5 x 24 = 3.6x10^-4 C

    3.6x10^-4/15x10^-6 = 24 V

    So is that right?
     
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