


Ultraviolet light frequencies are above violet on the spectrum and are invisible to the human eye. A black light bulb produces UVA light (as opposed to UVB light, which is much more harmful). How Sunburns and Sun Tans Work discusses ultraviolet light and its effects on our skin. Above violet is ultraviolet light, which we cannot see. Our eyes can see visible light in a spectrum ranging from red through orange, yellow, green, blue and violet. What you cannot see is the ultraviolet light that the bulb is also producing. If you turn on a black light bulb in a dark room, what you can see from the bulb is a purplish glow. We'll also see why black lights make some objects glow but not others, and we'll look at some interesting black light applications.

In this article, we'll find out exactly what's going on here. Many amusement parks use hand stamps that are invisible until you view them under black light. You may have also seen pieces of paper that look blank in regular light but spell out a glowing message under a black light. For example, if you have a fluorescent poster and shine a black light on it in a dark room, the poster will glow brightly.
