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Archived Planck's law and doppler effect

  1. May 4, 2013 #1
    Hello, We proved something during the course but I totally forgot how to do it..
    1. The problem statement, all variables and given/known data
    Prove that Planck's Law E=h*u is deduced from the equation of Doppler effect u'=u*√((1-β)/(1+β))
    2. Relevant equations
    Lorentz transformation


    3. The attempt at a solution
    If we take a beam of light of frequency u and an observer with speed Bc
    I don't know if it's correct..
    u'=u√((1-β)/(1+β))
    E'=y(E-B*Px*c)
    And px*c=E so
    E'=y(E-BE)
    =yE(1-B)
    =E√((1-β))/(√((1-β)/(1+β)))
    =E√((1-β))/√(1+β)
    E'=E*u'/u
    E'*u=E*u'
    E'/u'=E/u
    E/u=cste=h ?
     
    Last edited: May 5, 2013
  2. jcsd
  3. Jul 3, 2016 #2

    James R

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    I don't think that the energy of a photon can be derived solely from a consideration of the Doppler effect (relativistic or not). More information is needed.
     
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