Also, printed currency will "glow" under black lights. Or more specifically, the embedded strip with "USA 50 USA 50..." etc. will glow.
The strip is in different locations on different denominations, and will glow in different colors for different denominations.
Helpful in spotting "washed" bills that are actually a lower value.
Now if I could only remember where I saw the placement / color information... it's probably on the Bureau of Printing and Engraving site. ??? Sorry!
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Just a lowly 1st Year Law Student ("1L"), so don't take anything I say seriously!