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Energy of photons

  1. May 29, 2014 #1
    E=h*f (h constant of Planck,f frequency)

    What is the proof of that equation?
  2. jcsd
  3. May 29, 2014 #2


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    It agress with experiments.
    It is such a fundamental relation in physics that it is implicitly tested every day in lots of experiments and also a fair amount of engineering.
  4. May 29, 2014 #3
    Ok,thank you,but how scientist undestood that?
    Also how planck found this constant?
  5. May 29, 2014 #4


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    Staff: Mentor

    Last edited: May 29, 2014
  6. May 29, 2014 #5
  7. May 29, 2014 #6


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    Planck did not find the constant, he made an ansatz (an educated guess). He found that by making this ansatz, that there is some fundamental constant h and that the energy of a vibrational mode (of whatever is vibrating inside a black body) can only be in integer multiples of this constant times the frequency (nhf), he was able to solve the ultra-violet catastrophe. Subsequently, matching with experiment determined the numerical value of this constant.
  8. May 30, 2014 #7
    Thank you for your answers,everybody!!!
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