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Dispersion relation and Photonic Energy and Momentum Equations in QM

  1. Feb 7, 2010 #1
    Hi All,

    In quantum mechanics, related to photon, we have these two equations as valid ones:

    E = h x f

    p = h / lambda

    But we have in vacuum the dispersion relation c = lambda x f.

    1) How these relations change when the dispersion relation change ?

    2) Is it universally correct to write p = h x f / c ?

    Thanks ALL

    Best Regards

  2. jcsd
  3. Oct 10, 2010 #2
    Or still, is it correct to write:

    E = h c / lambda ?

    Best wishes

  4. Oct 11, 2010 #3


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    Science Advisor

    Yes, but at least c should be understood to mean not the vacuum velocity but the velocity of the wave in the medium.
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