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What gives photons the energy to move at the speed they do

  1. Nov 10, 2009 #1
    I have a question...
    what gives photons the energy to move at the speed they do?
     
  2. jcsd
  3. Nov 10, 2009 #2

    nicksauce

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    Re: photons...

    Photons always travel at the speed of light, regardless of their energy, because they are massless.
     
  4. Nov 10, 2009 #3
    Re: photons...

    A photon is pure kinetic energy. It alway travels at the speed of light, from the moment it is created. It's more accurate to say a photon has no rest mass than to say that it's massless.
     
  5. Nov 11, 2009 #4
    Re: photons...

    In wording that "what gives photons the energy", I wonder if the intent was to ask where the energy came from. There is always a source of the energy. If an electron in an atom drops to a lower energy state, for example, making a transition from the n=2 quantum number to the n=1 quantum number, it emits one photon. A nucleus that is in an excited state sometimes falls to a lower energy state, and gives off a gamma ray. An x-ray is given off when a moving electron hits a metal and loses its kinetic energy.
     
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