A to Z: Ultraviolet

This is the only subject that i could come up with that was interesting. I did think of being lazy and doing Ulna, and just a picture with an arrow pointing at the Ulna (which, in case you were wondering, is a bone in your forearm, the one closest to the torso).

So Ultraviolet light. I think the first thing we all think of is the purple light you see in clubs.
But do we know where it comes from and what it is?

Well, I think it may be best explained by a scientific diagram, done by the experts. So here's one for you.

This diagram shows the wavelengths of light. Visible light has a longer wavelength than UV light. UV light is found in sunlight and causes the melanin in our skin to darken when exposed to it, resulting in a tan, or sunburn depending how long you stay under the sunlight. It's also used in sunbeds for the same purpose.

UV has a lot of uses. Off the top of my head I can think of cosmetically, with ultraviolet nail polishes that glow (or fluoresce) under UV light. There is also a type of tattoo ink that does the same thing. There are pains that also do this.
You can also put a banknote under UV light and if it's british you'll be able the see the queen. There are other UV watermarks on things like driving liscences and passports.
Then theres imaging of things in space, forensic uses in crime scenes, air and water purification.
It's also used in reptile tanks.

Wikipedia has a page on it if you'd like more information and many many more uses. It may not be any good, but it's worth a try.

Ultraviolet is also a film starring Milla Jokovich. I have absolutely no idea what it's about.