How does ‘glow in the dark’ work?

Focus-Science and Technology - - Q & A - CHAR­LIE MACK, UCKFIELD ML

A lot of things can glow in the dark, in­clud­ing your wash­ing pow­der and of course those funky stars you stick on a child’s bed­room ceil­ing. They work through phe­nom­ena called phos­pho­res­cence and flu­o­res­cence. The ma­te­rial ab­sorbs en­ergy (usu­ally in the form of a par­tic­u­lar colour light) and then re­leases it as an­other colour light. Flu­o­res­cent ma­te­ri­als do this all at once, so when you shine UV light (from a torch or the Sun) on wash­ing pow­der it ab­sorbs the UV and then emits it as blue colour (which we as­so­ciate with clean cloth­ing, which is why the wash­ing pow­der peo­ple add it to the mix). Mean­while phos­pho­res­cent ma­te­ri­als, like glow-inthe-dark stars, do their emit­ting much more slowly. This en­ables them to shine for a few min­utes af­ter the bed­room lights are switched off.

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