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Homework Help: Initial voltage of capacitor

  1. May 8, 2017 #1
    1. The problem statement, all variables and given/known data
    I would like to know the initial voltage across the capacitor terminals in the following diagram.

    2. Relevant equations
    when a capacitor is connected to a DC source for a long time, it acts an open circuit.

    3. The attempt at a solution
    for t < 0, we get the diagram below and I believe the voltage should be 12V right?
    just making sure, cuz In an online solution it said the voltage is 0, if so why?
    Thank you

    Attached Files:

  2. jcsd
  3. May 8, 2017 #2


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    Staff: Mentor

    Before t = 0 the circuit is open at b. How could charge flow into the capacitor?
  4. May 8, 2017 #3
    but isn't one of the terminals of the capacitor connected to the 12V source?
    while the other is just simply disconnected.... shouldn't that incur a potential difference between the two plates
  5. May 8, 2017 #4
    never mind sir, I get it..... very silly mistake
    thanks though
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