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Homework Help: 2 capacitors connencted

  1. Apr 13, 2009 #1
    1. The problem statement, all variables and given/known data
    a capacitor C1 2.4uF charged to a voltage of 880V and a second capacitor C2 4.0uF charged to 560V. They are disconnected from their batteries and their positive plated and connected together, and their negative plated are connected together. What will the final voltage and charge on each be after a long time? They are then connected negative to positive..and same question as before.

    2. Relevant equations

    3. The attempt at a solution
    I don't really have a clue. However, I found the charge on each capacitor initially then added them together, and found the percent for each capacitor (C1/(C1+C2)) and times it by the total charge. Does that even make sense? because the answer was right. Are you able to add the capacitors in any way? are they in series or parallel? the voltages of them were the same as if they were in parallel. AH!
  2. jcsd
  3. Apr 13, 2009 #2


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    Staff Emeritus
    Science Advisor

    Find the charge Q1 on C1 and Q2 on C2.

    The total charge has to be conserved.

    Then find the combined capacitance in parallel, and find the voltage based on the total charge and effective capacitance.
  4. Apr 13, 2009 #3
    This works for the first case where the 2 positive ends are connected. In the second case where the positive is connected to the negative of the other it doesn't..whether you add the capacitances in parallel or series?! The voltage and charge on each is much smaller.
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