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Homework Help: Compton scattering, formulae question

  1. Nov 17, 2013 #1
    1. The problem statement, all variables and given/known data
    An X-ray source of wavelength gamma is directed at a sample; determine the maximum speed of scattered electrons.

    2. Relevant equations

    KE=([itex]\gamma[/itex]-1)mc2=hc/[itex]\lambda[/itex] - hc/[itex]\lambda[/itex]'

    3. The attempt at a solution

    I've been provided with the solution using the formula above, however it looks like it's Eincident - Escattered ---or in other words initial minus final...isn't convention final-initial? Why do we subtract initial minus final in this case?
  2. jcsd
  3. Nov 18, 2013 #2
    The final is subtracted because the scattered photon will have a lower energy than the incident photon (since some of it has gone to the electron).
  4. Nov 18, 2013 #3


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    Staff Emeritus
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    Apply conservation of energy to the situation.

    This question really doesn't belong in the advanced physics section.
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