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Homework Help: What is the potential difference between points a and b?

  1. Feb 23, 2008 #1
    1. The problem statement, all variables and given/known data

    Six identical capacitors with capacitance C are connected as shown in figure 30.68 (attachment). What is the potential difference between points a and b?

    2. Relevant equations

    C=Q/V

    3. The attempt at a solution

    The Cequivalent = 3/2 C

    Therefore, Q = CV
    = (3/2C)(12)
    = 18 C

    since capacitors in parallel have the same potential difference, the two capacitors that are in parallel between point a and b have the potential difference,

    V = Q/C
    = 18C/(C)
    = 18

    Thus, the two capacitors between point a and b, have a combined potential difference of 36V.

    Is this correct?
     

    Attached Files:

  2. jcsd
  3. Feb 24, 2008 #2
    any ideas?
     
  4. Feb 24, 2008 #3
    i don't know, i agree with most of what your saying, but haven't done any calculations yet.
    when i read 'potential difference' the first thing that i think of is subtraction.
    since both capacitors have the same potential, then the difference of their potentials is zero.
    but i could be wrong... and probably am.
    i only have one attempt remaining in mastering physics so i don't want to test this theory until someone else does.
     
  5. Feb 24, 2008 #4
    i was right,
    answer is 0 V
     
  6. Feb 24, 2008 #5
    got it, thanks!
     
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