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Do photons have mass?

  1. Jun 12, 2015 #1
    I read the FAQ about photons not having mass: Do photons have mass?

    But De-Broglie's equation says that wavelength=Plank constant / mass x velocity

    inserting values in the above relation we find the mass of a photon having certain wavelength
    Last edited by a moderator: Jun 14, 2015
  2. jcsd
  3. Jun 12, 2015 #2


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    Gold Member

    You wrote the debroglie equation for a massive particle (where you can write its momentum as p=mv which is not correct for the photon). You should use instead [itex] \lambda= \frac{h}{p}[/itex].
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