1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Electron oven In S-G Experiment

  1. Apr 13, 2008 #1
    Electron "oven" In S-G Experiment

    This isn't so much a homework problem but I guess it fits more here then in the other areas of the forum.

    Whilst we were deriving and expression for the deflection of particles in the Stern-Gerlach experiment, the lecturer stated that the particles emerge from the oven or furnace with 2kT energy, when asked why that was rather then 1/2kT, 3/2kT or anything in between, he could not recall the exact reason.

    Any idea why? I understand that the oven excites the particles to energies of the order of 3/2kT but then only particles in a particular direction are allowed to leave the oven, so I would expect the energy to be between 1/2kT and 3/2kT or if we include rotational energy it would be 2kT as mentioned, but is that the reason?

    This energy was then used to derive the velocity Vx along the x-axis (perpendicular to the screen)

  2. jcsd
  3. Apr 13, 2008 #2


    User Avatar

    In averaging the energy of the particles leaving the oven, you should include another factor of v_x in your integral.
  4. Apr 14, 2008 #3
    Sorry, could you specify which integral you are referring to? I realize that the distribution of velocities follows a maxwell-boltzmann distribution, neither the RMS, mean or Most probable velocity result in the correct answer, the only one which comes close is the Mean velocity with 2.5kT.
  5. Apr 15, 2008 #4


    User Avatar

    The average energy is calculated by an integral of (1/2)mv^2 times the M-B distribution.
    The rate of energy leaving the oven is the integral v_x times this, integrated from 0 to
    + infinity.
    You have to look in your textbook to see how these averages are calculated.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook