2. In a Compton scattering event, an incident photon is scattered by a free electron initially at rest. h (where h is the Plank constant; m.c (i) If the scattered photon acquires a wavelength 2' =- mẹ is rest mass of electron; c is free-space light velocity), show that the scattered photon propagates in a direction perpendicular to that of the scattered electron. If the scattered electron propagates with kinetic energy 127.8 keV in a direction opposite to that of the scattered photon, as shown in Figure 2. Find the angle 0, and therefore determine wavelengths of the incident and scattered photons, respectively. (ii) 180° – 0 λο Figure 2

2. In a Compton scattering event, an incident photon is scattered by a free electron initially at rest. h (where h is the Plank constant; m.c (i) If the scattered photon acquires a wavelength 2' =- mẹ is rest mass of electron; c is free-space light velocity), show that the scattered photon propagates in a direction perpendicular to that of the scattered electron. If the scattered electron propagates with kinetic energy 127.8 keV in a direction opposite to that of the scattered photon, as shown in Figure 2. Find the angle 0, and therefore determine wavelengths of the incident and scattered photons, respectively. (ii) 180° – 0 λο Figure 2