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Video:What Glows Under Black Lights?

with Anne Marie Helmenstine

It's fun to see what glows under black lights. Here, learn what glows under black lights before you turn one on.See Transcript

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Transcript:What Glows Under Black Lights?

There are a lot of everyday materials that fluoresce, or glow, when placed under a black light.

What Is a Black Light?

A black light gives off highly energetic ultraviolet light. You can't see this part of the spectrum, which is how 'black lights' got their name.

Common Materials That Glow Under Black Lights

Some common materials that contain fluorescent molecules include:
  • White Paper: White paper is treated with fluorescent compounds to help it appear brighter and therefore whiter
  • Petroleum Jelly: Petroleum jelly, such as Vaseline, glows a bright blue color under a fluorescent light
  • Club Soda or Tonic Water: The bitter flavoring of tonic water is due to the presence of quinine, which glows blue-white when placed under a black light
  • Body Fluids: Many body fluids contain fluorescent molecules. Forensic scientists use ultraviolet lights at crime scenes to find blood, urine, or semen
  • Vitamins: Vitamin A and the B vitamins thiamine, niacin, and riboflavin are strongly fluorescent
  • Chlorophyll: Chlorophyll makes plants green, but it fluoresces a blood red color
  • Antifreeze: Manufacturers purposely include fluorescent additives in antifreeze fluid so that black lights can be used to find antifreeze splashes to help investigators reconstruct automobile accident scenes
  • Laundry Detergents: Some of the whiteners in detergent work by making your clothing a bit fluorescent
  • Other Cleaners: Other types of cleaners that glow under black light include Irish Spring soap and Mr. Clean
  • Emperor Scorpion: The emperor scorpion normally is dark brown or black, but it glows a bright blue-green when exposed to black light
  • Tooth Whiteners: Tooth whiteners contain compounds that glow blue to keep teeth from appearing yellow
  • Postage Stamps: Stamps are printed with inks that contain fluorescent dyes
  • Jellyfish: A jellyfish, when exposed to black light in a darkened room appears to glow. Some of the proteins within a jellyfish are intensely fluorescent
  • Some Minerals and Gems: Fluorescent rocks include fluorite, calcite, gypsum, ruby, talc, opal, agate, quartz, and amber
  • Banana Spots: Black spots on a ripe banana appear to glow under a black light


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