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FEBRUARY 2, 2013
Science Saturday - Black Light Fun

A black light emits ultra violet light waves at the very end of the visible spectrum.  The UVA light from a black light has longer wave lengths than most visible light.  Don't tan under a black light as these longer waves penetrate further into the skin and may produce hydroxyl and oxygen radicals, aka skin cancer.  It would take a lot of time under a black light to get cancer.  Sir Isaac Newton first explained the idea of a light spectrum in his book Opticks written in the 18th Century.

The great thing about a black light is looking at different objects.  Anything white will appear to glow. Tonic water will glow blue under a black light.  The quinine in tonic water reflects the UVA light.  Many bodily fluids contain florescent materials and will also glow under a black light.  Forensic scientists use black light to detect blood at crime scenes.  If you crush a Vitamin B-12 tablet and dissolve it in vinegar it will glow yellow.  An empire scorpion will glow blue-green under a black light.  Maybe a blacklight is a good survival tool for the desert?  Canola oil will also glow under a black light.  Chlorophyll will glow red. 

Do you have a black light handy?  What have you found that glows in UVA light?

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posted by Arra, Lakewood Library


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