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Homework Help: Would the charges in each capacitors be the same ?

  1. Mar 14, 2010 #1
    Say there are 2 capacitors of different capacitance connected in series to a supply of 3 V . Would the charges in each capacitors be the same ?

    Can i say that charges are analogous current ? If so , since current is the same throughout the circuit , hence the charges in each capacitor is the same ?
     
  2. jcsd
  3. Mar 14, 2010 #2

    tiny-tim

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    Hi thereddevils! :smile:
    Not really.

    Use conservation of charge …

    if the charges were different, where would the extra charge have come from? :wink:
     
  4. Mar 15, 2010 #3
    Re: capacitors

    thanks , i just read bout it a little in wikipedia and it says the principle states that charges can neither be created or destroyed . So say in a circuit , there are 5C of charges so forever there will be 5 C of charges ? Where did this 5 C of charges come in the first place , is it from the battery ? And also each capacitor will store 5 C of charges following that principle ?
     
  5. Mar 15, 2010 #4

    tiny-tim

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    Hi thereddevils! smile:

    (just got up :zzz: …)

    The charge goes from one plate to another … the battery pumps charge all the way from the left-hand plate of the left-hand capacitor to the right-hand plate of the right-hand capacitor.

    The charge missing from one plate obviously equals the charge gained by the other plate.

    For the two "inside" plates, it's the same … the charge lost by one must equal the charge gained by the other.
     
  6. Mar 15, 2010 #5
    Re: capacitors

    thanks tim and good morning , its 5pm here in Malaysia .

    i kinda get the picture now so the function of the battery is to pump the charge , does it supply the charges ? Or the charges are already there in the circuit and the battery just pumps them around ?

    Ok i see , so when the capacitors are connected in series , the charges are equal in each capacitors , what if the capacitors are connected in parallel ? i think it will not be the same but rather the sum would give the overall charge of the circuit .
     
  7. Mar 15, 2010 #6

    tiny-tim

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    The latter … the electrons are already in the circuit, and all the battery does is pump them round.
    Yes, in parallel, the sum of the charges on the two left-hand plates (connected to one side of the battery) is equal and opposite to the sum of the charges on the two right-hand plates (and, of course, the voltage difference across each capacitor is the same).

    Have a good evening! :smile:
     
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