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RC Circuit Discharge Conceptual Question

  1. Mar 9, 2013 #1

    I have the solution manual, so this is more just a question of why, rather than what.

    I understand that with the switch open:
    vA = 3v
    vB = vC = 0v
    i0 = 0.25 mA

    When the switch closes it creates a short that makes the two 6kΩ resistors irrelevant. What I don't understand is why anything should change then. The solution manual tells me that a current would flow from the capacitor from B to C, but why? It seems like nodes B and C should be at 0v both before and after the switch is closed.
  2. jcsd
  3. Mar 9, 2013 #2


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    Gold Member

    Yes, node B is at zero both before and after the switch is closed, but after the switch is closed, what is the voltage across the capacitor? Is it any different than before the switch is closed?
  4. Mar 9, 2013 #3


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    Gold Member

    You are right--book is wrong.
  5. Mar 9, 2013 #4
    As far as I can tell the voltage across the capacitor should always be 3v.
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