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Homework Help: Find net capictance

  1. May 7, 2009 #1
    each capacitor has capictance c

    find net capictance b/w a and b

    http://img17.imageshack.us/img17/5720/13481036.gif [Broken]
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. May 7, 2009 #2
    Is that intersection in the middle a contact? Or are those two wires not crossing?
  4. May 8, 2009 #3
    yes there is connection between those 2 points
  5. May 8, 2009 #4
    Alright, well after some time passes there will be no current. You will have a voltage drop from A to B, called V. If there is one capacitor between A and B, then you know the drop across the capacitor is just V. So that helps you solve for 2 capacitors.

    The capacitor to the bottom left is useless since its voltage drop is just 0 (so its charge is 0).

    That leaves the top 3 capacitors. The first two are connected in parallel from A to the midpoint. Then they are connected in series with the last capacitor to B. Once you get the net capacitance there...

    You know those are now in parallel with the two capacitors we initially discussed. So you can just add their capacitances all up.

    Sorry about all the text, would have helped if you labelled the capacitors in the pic.
  6. May 16, 2009 #5
    thanks buddy , i got it.
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