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What is a photons rest-mass, at what speed does it move, and with what energy?
Question Date: 2007-06-19
Answer 1:

Photon rest mass is zero. Only things with rest mass zero can travel at the speed of light in a vacuum. Anything with a rest mass can't ever reach that speed. The energy is given by a quantum relation,
E = h*f,
where f is the frequency of the photon, h is Plancks constant.

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