. A photon maybe described classicaly as a particle of zeros mass possessing nevertheless a momentum h/λ=hν/c, and therefore a kinetic energy hν. If the phonon collides with an electron m at rest, ot will be scattered at some angle θ with an new energy hν′. Show that the change in energy is related to the scattering angle by the formula λ′−λ=2λcsin22θ, where λc=h/mc, is known as the Compton wavelength.
