48. If a 6.0 keV photon scatters from a free proton at rest, what is the change in the photon's wavelength if the photon recoils at 90 degrees?
52. A gamma ray of 700 keV energy compton-scatters from an electron. Find the energy of the photon scattered at 110 degrees, the energy of the scattered electron, and the recoil angle of the electron.
The Attempt at a Solution
48. Since the angle is 90 degrees, the change in wavelength should be one compton wavelength. I don't see where the energy of the photon comes into play.
52. Again, I don't see where the energy comes into play.