Finding a light source that produces an absorption spectrum?

[Persimmon]

This is an observational exercise where I have to find several different light sources and observe their spectra through a diffraction grating, then record my observations. I need two sources of each (i.e. continuous, emission, absorption).

Continuous and emission are fairly easy, but for the life of me I can't think what I could observe that would produce an absorption spectrum. I know that absorption spectra come about when there is an absorbing material like cool gas in front of a black body but I don't really know how I could find something like that. I thought maybe if I looked at a light source from far away in cold weather that might do it, but I still didn't see an absorption spectrum. Any help or hints would be much appreciated!

 

[ehild]

The sun itself produces absorption spectrum of its outer atmosphere: http://en.wikipedia.org/wiki/Fraunhofer_lines.

You can make a "light source" showing absorption spectrum by placing a coloured liquid (solution of some dye, or solution of KMnO4...) in front of a simple tungsten lamp.

ehild

 

[Persimmon]

Brilliant, thanks! I hadn't thought of that. I feel a bit stupid now.

 

[ehild]

Or it can be a colour filter glass or a simple coloured glass in front of the tungsten lamp...


ehild