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Basic physics of capacitance

  1. Dec 2, 2011 #1
    Hi. I'm trying to understand a couple of things.

    When you put a piece of metal on, say the cathode of a battery, I suppose there is a charge transfer from the battery to the metal because the electrons on the cathode have a high potential energy? And so if I connect a piece of metal to both the cathode and another one to the anode, one piece should recieve electrons and the other one should lose electrons.

    But I cannot make this fit with the capacitance formula Q=CV, because if the two metal pieces are infinitely far apart, C=0 and then no charge is induced at all.
  2. jcsd
  3. Dec 2, 2011 #2
    Why do you want your plates to be infinitely far apart?
  4. Dec 2, 2011 #3
    I think the "infinitely far apart" portion of your thoughts is the problem, not Q = CV. How do you connect two plates infinitely far apart to the same battery? How do you expect two objects infinitely far apart of exert an influence each other? Capacitance arises because two objects near each other effect each others' ability to store charge.
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