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Easy Electric Potentional Problem

  1. Sep 12, 2009 #1
    1. The problem statement, all variables and given/known data

    The electric potential difference between the ground and a cloud in a particular thunderstorm is 1.5E9 V. What is the magnitude of the change in the electric potential energy of an electron that moves between the ground and the cloud?

    _____ GeV

    2. Relevant equations

    U\q=V

    3. The attempt at a solution

    This should be simple.

    U=qV
    U=(1.6e-19)(1.5 GV)
    U=2.4e-19 GeV

    Why is this not right?
     
  2. jcsd
  3. Sep 13, 2009 #2
    Anyone? Still can't figure it out.
     
  4. Sep 13, 2009 #3
    NO one at all????
     
  5. Sep 13, 2009 #4

    Redbelly98

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    What are the units on the 1.6e-19? Include the units in the calculation.
     
  6. Sep 13, 2009 #5
    Coulombs. I'm not following.
     
  7. Sep 13, 2009 #6

    Redbelly98

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    Correct.

    That would make the units in your answer Coulombs*V, and not eV. You'll have to convert to eV (or GeV).
     
  8. Sep 13, 2009 #7
    So, ... what, I divide by 1.6x10^-19?

    U=2.4e-19 / 1.6e-19 = 1.5 GeV

    There are too many stupid units in electromagnetism! This is driving me crazy.
     
  9. Sep 14, 2009 #8

    Redbelly98

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    Yes. (Or don't multiply by 1.6x10^-19 in the first place.)

    Yes, you got it. :smile:

    You get used to it after awhile.

    By the way, if you use elementary charge units instead of Coulombs here, it's simpler:

    An electron has -1.00 elementary charges or -1.00 e of charge, so

    U = q V
    = (1.00 e) (1.5e9 V)
    = ___ eV
    = ___ GeV​
     
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