How can atomic emission spectra be useful?
The Atomic Emission Spectra usefulness can be compared to the usefulness of a fingerprint--- the atomic emission spectra finger print makes a unique identifier.
Using this unique identifer, we have found out how hot the stars are, as well as what type of elements were they made of. This led to the birth to modern astrophysics
To be inspired I recommend this:
Cosmos: Sisters of the Sun
The emission spectra of different elements are unique, so the spectra given off by hydrogen will be different than that of helium. The different colors of light produced by emission spectra of different elements allows them to be identified. One use of this technique is to identify the elements present in distant stars.
So elements can be identified by the colors their atoms produce when energy (by heating or electric current) is used to reveal their emission fingerprints. Analyzing the colors of light given off by stars reveals which elements are present in those stars.
Here is a look at emission (colors of light) produced by four different elements.
This video show uses diffraction grating to show the emission spectra of several elements including hydrogen, oxygen, neon and nitrogen.
Videos from: Noel Pauller
Use of a tool such as a spectroscope would allow someone to determine the different wavelengths each of these elements is giving off. The color you observe in the video is the sum total of all of the visible emissions from each element.
Hope this helps!