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Homework Help: AC Theory question with capacitors

  1. Mar 23, 2012 #1
    Three uncharged capacitors each of 1uF are connected in parallel and the combination connected to a 100V power supply via a 1MΩ resistor. After 2s the capacitors are removed, connected in series and the new combination allowed to discharge through a 10kΩ resistor.

    Find the discharge current at the start of discharge and 3ms late

    I was just thinking the general discharge equation:
    q=q e^(-t/RC)

    I have no idea where to go with it though so if any one can point me in the right direction id be very grateful
  2. jcsd
  3. Mar 23, 2012 #2


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    Staff: Mentor

    • Voltages in series add together.

    • Capacitances in series add according to: 1/C = 1/C1 + 1/C2 + ...

    Yes, that's what you use. First for the capacitors charging, then for them discharging. R and C will differ for the charging and discharging situations.
    Last edited: Mar 23, 2012
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