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Photoelectrics and kinetic energy

  1. Sep 16, 2012 #1
    Hello friends.

    I was just wondering why in photoelectrics, the kinetic energy of an electron released from a certain metal after being struck by a photon follows the classical approach and not the relativistic. For example...

    E_photon = (Planck_const)(frequency) = (Work function) + (1/2)(mass_electron)(u^2)

    instead of

    E_photon = (Planck_const)(frequency) = (Work function) + ((1 - ((u/c)^2)))^(-1)) - 1)(mass_electron)(c^2)

    I've read several texts, including my university's text and Serway's text but the answer isn't really there. Thanks in advance!
     
    Last edited: Sep 16, 2012
  2. jcsd
  3. Sep 16, 2012 #2

    PeterDonis

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    Staff: Mentor

    AFAIK all the photoelectric experiments that have ever been done have involved highly non-relativistic photoelectrons, so the classical formula works fine, but strictly speaking, it is an approximation and the relativistic formula is the strictly correct one.
     
  4. Sep 18, 2012 #3
    Cool, thanks Peter.
     
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