Two identical X-ray photons scatter elastically from free electrons
PHYSICS · Single correct · AP · Physics 2: Algebra-based · Modern Physics · Modern Physics
Problem
Two identical X-ray photons scatter elastically from free electrons. Photon A emerges at a 30∘ angle from its original direction, whereas photon B emerges at a 150∘ angle. Which statement best compares the energies EA and EB of the scattered photons?
(a) EA is less than EB because the smaller deflection angle means photon A transfers more momentum and therefore more energy to the electron.
(b) EA equals EB because total energy is conserved in the elastic scattering process.
(c) EA is greater than EB because photon A experiences a smaller increase in wavelength.
(d) EB is greater than EA because a photon that scatters backward gains energy from the recoiling electron through the Doppler effect.