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Energy stored in a capacitor

  1. Mar 6, 2011 #1
    1. The problem statement, all variables and given/known data

    [​IMG]

    Long time after closing K1,k2 and k3 the energy stored in each capacitor is?


    3. The attempt at a solution

    My method is to find out an expression for the current through the capacitor (of net capacitance 2C) at any time t and use I = CdV/dt to find out V across it at t=inf.

    However this method appears to be very long. Is there any shortcut?
     

    Attached Files:

  2. jcsd
  3. Mar 6, 2011 #2
    Yes. At T=inf the current through the capacitors is zero.
     
  4. Mar 6, 2011 #3

    SammyS

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    Also notice: that will leave you with a fairly simple circuit. The capacitors in combination with R3 are in parallel with R2[/SUB, but the voltage drop across R3 is zero since there is no current through it.
     
  5. Mar 7, 2011 #4
    So you mean voltage drop across any capacitor is V ?
     
  6. Mar 7, 2011 #5

    SammyS

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    No.

    As t → ∞ :

    The only current flowing is through R1 and R2.

    What is the voltage drop across R2?
     
  7. Mar 8, 2011 #6
    Its V/3
    Thank you!!
     
  8. Mar 8, 2011 #7

    SammyS

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    Correct !
     
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