An atom with mass m emits a photon of wavelength A.
(a) What is the recoil speed of the atom?
(b) What is the kinetic energy K of the recoiling atom?
(c) Find the ratio KIE, where E is the energy of the emitted photon. If this ratio is much less than unity, the recoil of the atom can be neglected in the emission process. Is the recoil of the atom more important for small or large atomic masses? For long or short wavelengths
(d) Calculate K (in electron volts) and KIE for a hydrogen atom (mass 1.67 x 10-27 kg) that emits an ultraviolet photon of energy 10.2 e V. Is recoil an important consideration in this emission process?