How is spectral analysis used in light sources?

Spectral analysis is a procedure in which a light source is shone through a lens to reveal its components. Light created by different methods have different spectral components, which act like a fingerprint. For example, if you examine the spectrum of a distant star, the different wavelengths will show you what different elements comprise that star.

At a more detailed scientific level, the individual lines are determined by the amount of energy lost by a particular atom's electrons as they move between energy levels. Each energy level of an atom's electron shell is characteristic to that atom. When an electron moves from a higher energy level to a lower one, there is a release of energy in the form of a photon, and that photon's wavelength is determined by the amount of energy change, resulting in a spectrographic line characteristic to that atom.