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Homework Help: Potential difference across each capacitor

  1. Feb 15, 2009 #1
    1. The problem statement, all variables and given/known data
    How many 1 microF capacitors connected in parallel would it take to store a total charge of 1 mC if the potential difference across each capacitor is 10.0V?


    2. Relevant equations
    C=Q/V
    in parallel --> Ceq=C1+C2+C3...


    3. The attempt at a solution
    I attemped this problem by first using the equation C=Q/V, using 1mC as my Q and 10V as my V. This gave me a total capacitance of 1*10^-4 F. I then divided this number by the capacitance of a single capacitor, 1*10^-6. This result showed that it would take 100 capacitors. I thought this answer seemed reasonable, but the next sentence in the problem tells me to diagram the parallel combination. I don't think they want me to draw out 100 capacitors in parallel. Can anyone double check my answer and tell me if it is correct?
     
  2. jcsd
  3. Feb 15, 2009 #2

    LowlyPion

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    Re: capacitance

    If you can write an equation like "Ceq=C1+C2+C3... skip a few +C100", what is your hesitancy in making a drawing like that?

    Trust your math.
     
  4. Feb 15, 2009 #3

    tiny-tim

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    Hi w3390! :smile:
    erm :redface:each capacitor! :wink:
     
  5. Feb 15, 2009 #4
    Re: capacitance

    If I do trust my math, I will be drawing out 100 capacitors on parallel on my sheet of paper. Does this sound reasonable to you?
     
  6. Feb 15, 2009 #5

    LowlyPion

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    Re: capacitance

    Sounds tedious when an ellipsis will do.
     
  7. Feb 15, 2009 #6
    Re: capacitance

    Does this mean that the potential difference across the entire combination will be 1000V by multiplying the number of capacitors by the drop across each one?

    Never mind, I figured it out. Thanks.
     
    Last edited: Feb 15, 2009
  8. Feb 15, 2009 #7

    tiny-tim

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    Yes, but it's not 1000V … call the number of capacitors n, and see how many times n comes into the equation. :wink:
     
  9. Feb 15, 2009 #8
    Re: capacitance

    I'm getting 1x10^-5 F for total capacitance. So 10 of the 1microF capacitors in parallel. Assuming you meant "total charge of 1mC" to mean micro-Coulomb and not milli-Coulomb. Otherwise it's like 10,000 capacitors.:bugeye:
     
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