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Analyzing equivalent capacitance

  1. Mar 8, 2013 #1

    I am looking for some strategies for figuring out the best way to approach problems asking me to find the equivalent capacitance when given a daunting looking circuit with capacitors arranged in all sorts of funny ways, especially when issues come up of capacitors not contributing to the equivalent capacitance because they aren't even being charged up.

  2. jcsd
  3. Mar 8, 2013 #2

    jim hardy

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    Science Advisor
    Gold Member

    Just like you would for resistors, except of course the arithmetic is swapped around:
    Resistors in series add
    resistors in parallel - their reciprocals add.

    capacitors in parallel add
    capacitors in series- their reciprocals add.
    That's because when you calculate C into ohms of reactance, C is in the denominator.

    Backing up a bit - The general rule is: Impedances(ohms) in series add; conductances(mhos) in parallel add.

    Was that the question?
  4. Mar 8, 2013 #3
    No, I mean how to I combine the capacitors to make an equivalent capacitor. I see this and don't even know where to begin, my question is how to systematically approach these types of problems.
  5. Mar 8, 2013 #4


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    Staff: Mentor

    When a circuit is too complicated for me to intuitively figure out, I just resort to writing and solving the KCL simultaneous equations. That's the systmatic approach that I use.
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