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Homework Help: Rms velocity of electron in free space?

  1. Mar 19, 2016 #1
    1. The problem statement, all variables and given/known data
    How many orders of magnitude smaller is the average drift velocity of a hole than the RMS thermal velocity of an electron moving in free space? (Use the law of equipartition to find the RMS thermal velocity of a free electron.)

    This is the last part of the problem, I have already found the drift velocity to be 2.5 x 10-4

    2. Relevant equations
    vrms = √3kT/m
    This is for an ideal gas, so I'm not sure if it applies.

    3. The attempt at a solution
    I know I need to find the energy of an electron, but I can't seem to find anything about how to calculate that in a vacuum, just how to find it based on pressure and temperature.
  2. jcsd
  3. Mar 19, 2016 #2


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    Staff: Mentor

    Electrons in free space are close to a perfect gas. You can probably assume room temperature.
  4. Mar 19, 2016 #3
    Ok, with those assumptions I get 110,000 m/s, which is 9 orders of magnitude higher than the drift velocity. Thanks
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