plelike.blogg.se - How does the light bulb work

The "black" glass tube itself blocks most visible light, so in the end only benign long-wave UV-A light, along with some blue and violet visible light, passes through. This coating absorbs harmful shortwave UV-B and UV-C light and emits UV-A light (in the same basic way the phosphor in a fluorescent lamp absorbs UV light and emits visible light).

A tube black light is a basically a fluorescent lamp with a different sort of phosphor coating.

In the next section, we'll see how phosphors are used in regular fluorescent lighting and in black lights. A phosphor converts the energy in the UV radiation from a black light into visible light. What you see glowing under a black light, whether on a fluorescent poster or an invisible hand stamp or a newly washed white T-shirt, are phosphors.Ī phosphor is any substance that emits visible light in response to some sort of radiation.

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.