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Van de Graaff generator energy question

  1. Jun 15, 2005 #1
    I would appreciate help with this problem:
    If a Van de Graaff generator is charged to 50,000 volts, how much
    energy does it take to add an additional electron to the charge on the
    sphere? (I know that the charge on an electron is -1.6 x 10^-19 C)
  2. jcsd
  3. Jun 15, 2005 #2

    Chi Meson

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    A volt is a "joule/coulomb"

    You got volts, you got coulombs, you want joules.
  4. Jun 23, 2005 #3
    So I multiplied 50000 x -1.6x10^-19
    and I get for an answer: -8x10^-18 joules
    Does that look right?
  5. Jun 24, 2005 #4


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    Your exponent is not correct. If the sphere is negatively charged to begin with, to add another electron will require positive work. The original 50,000V potential of the sphere would actually be negative. I'm not sure what the intent of the problem is. "Additional electron" hints that it was negatively charged to begin with, but the positive voltage suggests it was positive.
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