Let a particle of charge e and rest mass m, initially at rest in the laboratory, scatter a photon of initial frequency νi. This is called Compton scattering. Suppose the scattered photon comes off at an angle θ from the incident direction. Use conservation of four-momentum to deduce that the photon’s final frequency νf is given by 55 2.9 Exe rcises
1 νf = 1 νi + h �1 − cos θ m �