Black light

[daniel_i_l]

Why does black light (florecent light without the coating) light up only white things?

[KingNothing]

http://science.howstuffworks.com/black-light.htm

[moose]

I believe what you are asking is the same type of question as:
"Why does red light only light up red and white things?"
I think it's the same answer too ;)

Whatever howstuffworks says is probably more correct and thorough

[DaveC426913]

I believe what you are asking is the same type of question as:
"Why does red light only light up red and white things?"
I think it's the same answer too ;)
Um, if that were true, the object would only emit UV. In fact, it is emitting a different wavelength than that which it is absorbing.

[moose]

Um, if that were true, the object would only emit UV. In fact, it is emitting a different wavelength than that which it is absorbing.
Yes, but read this
UV light waves are too short for us to see -- they are completely invisible -- so fluorescent lamps have to convert this energy into visible light. They do this with a phosphor coating around the outside of the tube.

Phosphors are substances that give off light -- or fluoresce -- when they are exposed to light. When a photon hits a phosphor atom, one of the phosphor's electrons jumps to a higher energy level, causing the atom to vibrate and create heat. When the electron falls back to its normal level, it releases energy in the form of another photon. This photon has less energy than the original photon, because some energy was lost as heat. In a fluorescent lamp, the emitted light is in the visible spectrum