where is the phosphor coating on a black light?

Question

is it on the inside of the wood's glass & wat is its function? cheers. =D

Answer 1

As with all fluorescent tubes, the coating is on the inside surface of glass. The electrical gas discharge emits primarily ultraviolent light. To turn it into visible light, a phosphor is used. This absorbs UV, and re-emits in in the visible. WIth a black light, the phosphor is chosen to re-emit in the UV too, and the tube is made of a type of glass (wood's glass) that passes this UV, but blocks most visible light that is produced by the discharge.

Answer 2

A mercury vapor light will produce UVA and UVB. It is made the same way as a fluorescent light except the coating on the inside of the fluorescent bulb converts the uv light to visable. In a black light, the coating blocks the harmful (to you) uv and lets the less harmful uv through. This is not very efficient. The mineral lights which produce uv do so by using a special glass filter to let one of two ranges of black light through. This mounts between the mercury vapor light and what you are shining the light on/ If you remove the filter and look at the bare mercury light, it will harm your eyes.