Photoelectron spectroscopy applies the principle of the photoelectric effect to study orbital energies of atoms and molecules. High-energy radiation (usually UV or x-ray) is absorbed by a sample and an electron is ejected. The orbital energy can be calculated from the known energy of the radiation and the measured energy of the electron lost. The following energy differences were determined for several electron transitions:
Calculate $\Delta E$ and $\lambda$ of a photon emitted in the following transitions: (a) level $3 \rightarrow 2 ;$ (b) level $4 \rightarrow 1 ;$ (c) level $5 \rightarrow 4$.