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2. (a) Calculate the wavelength of a 120 MeV photon. (3) (b) It is found that photo-electrons are emitted from a material, only if light with a wavelength of less than 541.415 nm is shone onto it. If light with a wavelength of 329.2 nm is shown onto the material, what is the maximum possible kinetic energy of the emitted photo-electron? (3) (c) Determine the distance of closest approach of 1.00 MeV alpha-particles incident on a silver nucleus (Z = 47). (d) X-rays are incident onto a powder sample and diffract at an angle of 15° relative to the incident direction as shown in Fig. 1. If the X-ray photons have an energy of 15 ke V, calculate the distance between the lattice planes. (5) (e) The Compton scattering formula is: h X-X= (1 -cos) An X-ray with a wavelength of 0.010 nm scatters from a gold target (Z = 79). What is the kinetic energy of the most energetic recoil electron and at what angle does it recoil? mc