An incident photon with energy scatters from a stationary free electron
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Modern Physics · Modern Physics
Problem
An incident photon with energy 200keV scatters from a stationary free electron. Two possible scattering angles are considered: 30∘ and 120∘. A detector measures the energies of the scattered photons and finds them to be 190keV for 30∘ and 150keV for 120∘.
Use these measurements to analyze the recoil electrons produced in the two cases.
(a) Calculate the kinetic energy of the recoil electron for each scattering angle.
(b) Determine the ratio KE30∘KE120∘ of the two kinetic energies.
(c) Provide a qualitative explanation, based on conservation laws, for why the kinetic energy of the recoil electron depends on the scattering angle in the way quantified by your result in part (b).