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Thermal Radiation. Quantum Nature of Light.

Problem 5.281

Using the conservation laws, demonstrate that a free electron cannot absorb a photon completely.

Reveal Answer
5.281. Let us write the energy and momentum conservation laws in the reference frame fixed to the electron for the moment preceding the collision with the photon: ℏω+m0c2=mc2,ℏω/c=mv,\hbar \omega+m_{0} c^{2}=m c^{2}, \hbar \omega / c=m v, where m=m0V1−(v/c)2‾.m=m_{0} V \overline{1-(v / c)^{2}} . From this it follows that v=0v=0 or v=cv=c The results have no physical meaning.
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