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Homework Help: Closing a Circuit

  1. Apr 10, 2010 #1
    24.89 Giancoli

    There are three capacitors. One is in parallel with two others. The two others are in series. The alone one is 2.8 uF, the other two in series are 4.4 and 3.7 uF. a 12 volt voltage is applied. Initially there is a bridge that connects to the 2.8. After it is charged, the switch is thrown. What are the final charges on each?

    This one throws me because I'm not sure what happens after the switch is thrown. Does the voltage cease to be applied? or is it still applied? if it is still applied, then I'm not sure how the built-up charge in the 2.8uF capacitor matters.
     
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  3. Apr 10, 2010 #2

    kuruman

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    I can imagine a single capacitor in parallel with a series combination, but I cannot imagine what the "bridge" does or where the switch is. Can you post a circuit schematic?
     
  4. Apr 10, 2010 #3
    GIANCOLI.ch24.p89.jpg
     
  5. Apr 10, 2010 #4

    kuruman

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    OK, I get it. With the switch to the left, C1 is fully charged and the other two are uncharged. When the switch is thrown to the right, the voltage source is disconnected and the charge that was initially on C1 is now shared by C1 and the series combination of C2 and C3. Obviously, C1 has less charge than before because some of it went to the series combination.
     
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