- (a) Outline why Compton scattering offers better evidence for the particle nature of light than the photoelectric effect. [2]
The figure shows a photon of wavelength 6.40 × 10⁻¹² m and energy 0.194 MeV incident on an electron at rest. The photon scatters at an angle θ with wavelength 7.47 × 10⁻¹² m. The electron recoils.
Compton‑scattering diagram with incident photon, scattered photon at angle θ, and recoiling electron
(b) Outline why the wavelength of the scattered photon is longer than that of the incident photon. [2]
(c) (i) Show that the energy of the scattered photon is about 0.17 MeV. [1]
(ii) Calculate the kinetic energy of the recoiling electron. [1]
(iii) For an electron, h/(mₑc) = 2.43 × 10⁻¹² m. Determine θ. [2]