Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: The Two-Capacitor Problem

  1. Jun 23, 2004 #1
    This is most likely a well known problem. I think that I could deal with its basic aspects such as calculating the magnitude of the potential difference across each capacitor, the potential energy store in the two capacitor after the switch is close, ect, if I could determine whether the two capacitors are connected in series or in parallel once the switch is close.

    If I treat the charged capacitor as an emf source, I am led to think that the two capacitors are connected in series. However, if I consider the arrangement as two capacitors, then I see them as paralllel connected.

    Can anyone give me an idea how to determine whether the two capacitors are in series or in parallel once the switch is closed.

    Refer to the following for a diagram of the circuit.


    Thank you for your help,

    Last edited by a moderator: Apr 21, 2017
  2. jcsd
  3. Jun 23, 2004 #2
    When you close the switch the capacitors are connected in parallel.

    Good luck
  4. Aug 2, 2004 #3
    They are simultaneously in series (same current) and in parallel (same voltage).

    The solution to the problem requires that you first recognize that the model likely being used is that of an “ideal” circuit (i.e., lumped circuit theory). In applying lumped circuit theory, we distinguish between the electrical properties (resistance, capacitance, and inductance) and physical circuit elements (resistor, capacitor, and inductor). If you bear that in mind, and then carefully apply Kirchoff’s Laws, you will arrive at the answer. (See the discussion http://www.ilovephysics.com/cgi-bin/index.cgi?action=forum&board=conceptdiscadv&op=display&num=50 [Broken]).

    Last edited by a moderator: May 1, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook