Experimental Modern and Quantum Physics for Do-It-Yourself Science Enthusiasts 

Today I received an UltraFire WF-502B UV flashlight advertised as emitting at 365 nm.  I was wondering how to tell if it really does, especially since vendors commonly list it as emitting 365-400 nm.

Well, I was in Canada last week, and had $25 Canadian left over in my wallet, so I tried this flashlight and compared it to the fluorescence produced by an Inova X5MT-UVT 400 nm flashlight.  Much to my surprise, the 365 nm UltraFire caused fluorescence that did not show up at all under the Inova 395 nm flashlight.

To make sure that the difference in fluorescence wasn’t due to wash-out by additional white light, I used a UG-1 UV filter (325nm – 385nm bandpass), and obtained the same results.

So there, a $5 Canadian note will make a very useful wavelength-sensitive detector to tell your UV LEDs apart.

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