Consider a hydrogen atom.
(i) Calculate the energy (in eV) of the n=4 stationary state.
(ii) The electron jumps directly from n=4 to n=2. Calculate the corresponding photon wavelength.
(iii) A student redraws the energy–level diagram on a large sheet, choosing a scale in which 1cm represents 2.0eV on the vertical axis. On this scale, determine the vertical length (in cm) that the student should mark to represent the photon energy obtained in part (ii). State whether this photon lies in the ultraviolet, visible or infrared region.