How do black lights work?

Black lights may look just like normal fluorescent lamps or incandescent light bulbs, but they do something completely different. Switch one on, and white clothes, teeth and various other things glow in the dark. read more

A black light looks dark purple, but most of the light it emits is in the ultraviolet (UV) range of the spectrum, which is invisible to the human eye. Under a UV light, white clothes, our UV poster [link], glow in the dark and many fluorescent coloured items emit a bright glow. read more

A black light works by producing UVA light, or ultraviolet light, that we cannot see. Ultraviolet light is above the spectrum of visible light that our eyes can process. When objects appear to glow under the light, they are substances that are emitting light in response to radiation. read more

If you turn on a black light bulb in a dark room, what you can see from the bulb is a purplish glow. What you cannot see is the ultraviolet light that the bulb is also producing. Our eyes can see visible light in a spectrum ranging from red through orange, yellow, green, blue and violet. Above violet is ultraviolet light, which we cannot see. How Sunburns and Sun Tans Work discusses ultraviolet light and its effects on our skin. read more

Black lights work on this same principle. There are actually two different types of black light, but they work in basically the same way. A tube black light is a basically a fluorescent lamp with a different sort of phosphor coating. read more