why do things glow under a blacklight

Do you like to? How about? Did you know that both of those activities can be way more
if you do them in the dark under a black light? When that happens, you're set for some! Whether you've been glow or experienced the glow-in-the-dark effects of a black light at a skating or an amusement park, you know what a cool and sensation it is to see your clothing glow like it's. What's going on here? Are black lights? Nope! They're simple tools that take advantage of science. Let's take a closer look at black lights and why they make things glow. Black lights are made in much the same way that regular or lights are made. The primary difference is in the, coatings, or filters that are used in black lights. Black lights use these different materials so that most of the light emitted is ultraviolet (UV) light with just a bit of light in the wavelengths closest to the UV ( and violet).


That's why black lights usually appear dark blue or purple. Ultraviolet light can't be detected by the naked eye. We're surrounded by UV light every day when we enjoy the rays of the Sun. Although UV light has some applications, we must be careful to avoid, which can lead to increased risk of, eye damage, and skin aging. When UV light bounces off objects that contain special substances called phosphors, interesting things happen. Phosphors are substances that emit light in response to radiation. Phosphors hit by UV light become excited and naturally fluoresce, or in other words, glow. In addition, although your eyes can't see the UV light as it leaves the black light, some of that UV light that gets reflected back to your eyes after hitting the phosphors now has less energy and falls within the range. These factors combine to produce the glow-in-the-dark effects you're familiar with.


There all sorts of phosphors, both natural and man-made. For example, your teeth and fingernails contain phosphors, which explains why they glow under a black light. There are also many man-made phosphors found in fabrics, paints, and building materials. That's why certain clothing and objects look so cool under a black light. Black lights have many practical applications beyond simply having while, dancing, or roller skating. Forensic experts, for example, can use black lights to examine crime scenes for evidence of bodily fluids, such as blood. Law enforcement officers can use black lights to identify counterfeit money, as well as forgeries of antiques and artwork. Santos, The colors of light that the human eye is able to see range roughly from red to blue in color. Blue light has a higher frequency than red light. The light which has frequency just lower than red light is called "infra-red", and the light which has frequency just higher than blue light is called "ultra-violet".


Both infra-red and ultra violet-light are beyond our eyes' range for efficiently detecting, however they are still very important. Infra-red light is often used to warm things (like heat lamps over food in restaurants), and ultra-violet light is the subject of your question. A "black light" is just a light bulb designed to emit ultra-violet light. The reason these are called "black" is that if you look at the actual bulb it does not seem very bright (sort of a dim violet color), and if you put a black light in a dark room it really does not brighten it very much. the room remains almost black. These bulbs do emit lots of light however, its just that we cant see it. Some materials have the special property that they absorb ultra-violet light and then re-emit the light at lower frequencies that our eyes CAN see.


This is called "fluorescence". These materials are sometimes found on our t-shirts, jackets or shoes, and when we walk near a black-light they will seem to "glow" since they are translating the invisible ultra-violet light into easy to see colors, most often white. If you have a black-light handy, why dont you do the following experiment: Try putting different kinds of materials near it and make a list of which ones glow brightest and what color you see. Once you do this, tell us your results (use this web page again) and will post them for everyone in the world to see. Some of the materials you might try are different foods and drinks, plastics, bleach (ask your mom or dad first), dirt. whatever you can think of. Let us know how it works, MS (published on 10/22/2007)

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