A hydrogen atom is excited from a state with n = 1 to one with n = 4.
(a) Calculate the energy that must be absorbed by the atom.
(b) Calculate and display on an energy-level diagram the different photon energies that may be emitted if the atom returns to its n = 1 state.
(c) Calculate the recoil speed of the hydrogen atom, assumed initially at rest, if it makes the transition from n = 4 to n = 1 in a single quantum jump.