This tool disperses and even separates wavelengths. All elements emit and absorb wavelengths. These act as a fingerprint for each element. Three types of these are continuous which consists of solids, liquids, and dense gases that emit light of all wavelengths, there is also emission which consist of gases that emit light of only a few wavelengths, finally there is absorption which consists of a source a thin gas absorbing lights.
This is were solids, liquids, and dense gases emit light of all wavelength.
Gases emit light of only a few wavelengths.
If there is a source of a thin gas will absorb light of light behind it of the same wavelengths it emits.
Why are spectra's used?
We find these spectra's to be important because we can identify stars and how they are and if we go look for these it will be easy. We know exactly each form.