Why do black lights look purple?
BLACK LIGHTS / LOOK PURPLE BECAUSE THEY GIVE OFF ULTRAVIOLET LIGHT. A black light gives off ultraviolet light. It looks purple, but the ultraviolet rays being emitted from the bulb are invisible. In the case of an inexpensive incandescent bulb (left), the rays are actually being given off by the paint on the bulb; fluorescent black lights (more expensive) generate UV light from the gas inside, and do a better job. Ultraviolet light is ‘beyond violet’ on the spectrum. It’s just like visible light, except it’s more energetic, and our eyes can’t see it. Black lights actually produce small amounts of a type of ultraviolet light called UVA. (The kind from the sun that tans your skin is UVB).
