It consists of a number of bright bands with a sharp edge at one end but fading out at the other end.
Band spectra are obtained from molecules. It is the characteristic of the molecule. calcium or barium salts in a bunsen flame and gases like carbon-di-oxide, ammonia, and nitrogen in molecular state in the discharge tube give band spectra. When the bands are examined with high resolving power spectrometer, each band is found to be made of a large number of fine lines, very close to each other at the sharp edge but shaped out at the other end. Using band spectra the molecular structure of the substance can be studied