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Voltage of a battery and capacitors are the same

  1. Mar 11, 2014 #1
    I was watching this video: http://www.youtube.com/watch?v=P8A1U-RZDao&index=7&list=PLLUpvzaZLf3Jv7AjU5pfY8s25-QBCfdIZ
    and at around 6 minutes, I got confused. Ill summarize it below in case the link does not work:

    If you have a circuit which consists of a battery which is 12 volts, and a lot of capacitors…what is the voltage of the capacitors? Are ALL of them 12 V regardless of how they're set up, and the size of it? I heard something about capacitors taking their "Maximum voltage" always.

    Also, how would this change if you add a 4V light bulb?
     
  2. jcsd
  3. Mar 11, 2014 #2

    mfb

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    Staff: Mentor

    Did you mean to link the video "Dielectrics in Capacitors and Otherwise" or something else? The video does not look related to your questions.

    It depends on the circuit. If their terminals are connected to the terminals of the battery (via a cable as in 6:00), they will charge to 12 V.

    It acts like a resistor, and will slow the charging process. It should not change the final voltages if it is a regular light bulb (i.e. not LEDs).
     
  4. Mar 11, 2014 #3
    I can't find the correct video for some reason . I ll check later.

    Suppose you have something like this:

    Figure_20_05_10a.jpg

    and it's connected to a battery . Would ALL the capacitors have the same voltage across it?
    I'm mainly confused on problems like: "you stick a 12 volt battery to a circuit like this…now find the capacitance of each capacitor". Like what would you need to know to solve it?
     
  5. Mar 11, 2014 #4

    mfb

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    Staff: Mentor

    No.
    As an example, if the leftmost two capacitors would both have 12V across it, the total voltage across this side would be 24V - but we know the two sides have a difference of just 12V.

    In addition, the same voltage for both capacitors would violate charge conservation if we start charging it from zero.

    Just charge conservation, Q=CV and knowledge that the potential is the same everywhere in a wire.
     
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