Question

How can the difference in brightness of spectral lines be explained?

Answer 1

The spectral lines are formed as a result of the energy emitted by the electrons when they fall back to n=2 shell. The higher the energy released by the electron, brighter the spectral line formed. That means if an electron that has been excited to much higher energy level relaxes the spectra formed by that would be brighter than others, those which have relaxed from lower energy levels.

There would be various lines in an elements' spectra. Some elements will have more no. of lines in there spectra too. There may be combination of dark and bright lines in the spectra. All depends on the energy which is released by the electron as it relaxes.

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