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I The energy of a photon?

  1. Jun 29, 2016 #1
    please look at he underligned formula. is it a axiom we have to ake for granted ?

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  3. Jun 29, 2016 #2


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    Staff: Mentor

    No, we can and have measured this as far as I know.
  4. Jun 29, 2016 #3
    I think i got it
    -De broglie : p=h/(the wace longitude:L)
  5. Jun 29, 2016 #4


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    Staff: Mentor

    For relativistic particles, the general relationship between energy, momentum and mass is $$E = \sqrt {(pc)^2 + (mc^2)^2}$$ where m is the invariant mass (often called the "rest mass"). For photons, m = 0 which leads to E = pc.
  6. Jun 30, 2016 #5
    thanks a lot @jtbell :smile:
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