An atom with mass m emits a photon of wavelength l.(a) What is the recoil speed of the atom? (b) What is the kinetic energyK of the recoiling atom? (c) Find the ratio K/E, where E is the energy ofthe emitted photon. If this ratio is much less than unity, the recoil of theatom can be neglected in the emission process. Is the recoil of the atommore important for small or large atomic masses? For long or shortwavelengths? (d) Calculate K (in electron volts) and K /E for a hydrogenatom (mass 1.67 * 10^-27 kg) that emits an ultraviolet photon of energy10.2 eV. Is recoil an important consideration in this emission process?

An atom with mass m emits a photon of wavelength l.(a) What is the recoil speed of the atom? (b) What is the kinetic energyK of the recoiling atom? (c) Find the ratio K/E, where E is the energy ofthe emitted photon. If this ratio is much less than unity, the recoil of theatom can be neglected in the emission process. Is the recoil of the atommore important for small or large atomic masses? For long or shortwavelengths? (d) Calculate K (in electron volts) and K /E for a hydrogenatom (mass 1.67 * 10^-27 kg) that emits an ultraviolet photon of energy10.2 eV. Is recoil an important consideration in this emission process?