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Homework Help: Momentum of photon

  1. Sep 22, 2011 #1
    1. The problem statement, all variables and given/known data

    Photon dont have mass. But they possess momentum.

    2. Relevant equations



    3. The attempt at a solution
    Momentum is product of mass and velocity. Then how photons which dont have mass can have momentum?
     
  2. jcsd
  3. Sep 22, 2011 #2

    gneill

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    Staff: Mentor

    Momentum is a product of mass and velocity only for things that have rest mass. For things without rest mass (like photons) another expression holds.
    [tex] p = \frac{h \nu}{c} = \frac{h}{\lambda}[/tex]
     
  4. Sep 22, 2011 #3
    Thanks gneill for your clarification
     
  5. Sep 22, 2011 #4

    ehild

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    Homework Helper

    The momentum of the photon can be written also as p=mc, where m=E/c2. (And E=hν)

    ehild
     
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