PHYSICS · Single correct · AP · Physics 2: Algebra-based · Modern Physics · Modern Physics
Problem
In a detailed Compton-scattering study, data for small scattering angles lie on a straight line, but for angles above 120∘ the measured Δλ values are systematically larger than those predicted by the extrapolated line. Which of the following explanations is most consistent with this upward deviation at large angles?
(a) The linear approximation used to relate Δλ to scattering angle breaks down above about 120∘; higher-order terms in θ make the true curve rise more steeply.
(b) At large angles the finite angular resolution of the apparatus leads to an overestimate of θ, which in turn makes the computed Δλ appear larger.
(c) Some photons undergo multiple scatterings before reaching the detector, producing larger apparent wavelength shifts at high angles.
(d) The recoil electron’s relativistic energy correction, neglected in the simple formula, becomes important above 120∘, giving larger Δλ than the basic Compton prediction.