Spectral line by Ciro Santilli 37 Updated +Created
A single line in the emission spectrum.
So precise, so discrete, which makes no sense in classical mechanics!
Has been the leading motivation of the development of quantum mechanics, all the way from the:
Spectral line by Wikipedia Bot 0
A spectral line is a dark or bright line in a spectrum, representing the absorption or emission of light at specific wavelengths by atoms or molecules. Spectral lines occur when electrons in an atom or molecule transition between energy levels; they either absorb or emit photons with wavelengths that correspond to the energy difference between those levels.

New to topics? Read the docs here!