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Homework Help: Series versus Parallel Capacitors

  1. Feb 26, 2009 #1
    This is not so much a homework as just a general question.

    I understand the reasoning behind capacitors in a series all of have same charge, which consequently causes each one to have a separate voltage. But why do capacitors in parallel not have the same amount of charge. They all receive the same voltage. Even though capacitance can differ among capacitors in a series, they still all have the same charge. Why would capacitance affect the charge of capacitors in parallel differently?
  2. jcsd
  3. Feb 26, 2009 #2


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    Gold Member

    Remember that voltage is a measure of how 'hard' the current pushes, not the amount. The current in a parallel series is split, so why wouldn't the amount of charge be split too? Basically current is the net flow of electrons in some time. so when the amount of electrons in some time vary for the entire circuit why wouldn't the amount of electrons stored in any one capacitor be different.

    Someone correct me if I'm off on some definition here but I believe the idea is correct. My electricity is a tad rusty but this answer seemed the most obvious to me.
  4. Feb 27, 2009 #3
    is it possible for two capacitors the following two capacitors to exist: one has a capacitance of 4F and a charge of +q, and the other has a capacitance of 2F and a charge of +5q.

    I think that is it because capacitance is simply a constant that describes the rate of change of charge per unit voltage. If the +5q capacitor has a voltage of 5v, then the two capacitors would be feasible.

    Since factors such as dielectrics, area and distance determine the capacitance, then it it possible for the two capacitors to exist.

    Can anyone give me a hand on this one?
  5. Feb 27, 2009 #4


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    A capacitor is something that holds charge. If you add a couple in parallel then it's like you have more than one cup lined up to pour charge into.

    Q = V*C

    or just looking at the capacitor it's C = Q/V.

    As you noted if they are in series the charges equalize across the equivalent capacitor, and the lower voltage at each yields lower charges at each. (The equivalent capacitance is less, the reverse of when they are in parallel.)
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