Solution to task 629 from Chertov´s for extramural stud

Solution to task 629 from Chertov´s for extramural stud

629. The average lifetime t of an atom in an excited state is about 10-8 s. At the transition of an atom to the normal state, a photon is emitted, the average wavelength <λ> of which is 400 nm. Estimate the relative width Δλ / λ of the emitted spectral line, if there is no line broadening due to other processes.