Today’s Wonder of the Day was inspired by caden. caden Wonders, “why dose black light make my socks glow?” Thanks for WONDERing with us, caden!
Do you like to roller skate? How about bowling? Did you know that both of those activities can be way more fun if you do them in the dark under a black light? When that happens, you're set for some glow-in-the-dark fun!
Whether you've been glow bowling or experienced the glow-in-the-dark effects of a black light at a skating rink or an amusement park funhouse, you know what a cool and eerie sensation it is to see your clothing glow like it's radioactive.
What's going on here? Are black lights magic? 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 incandescent or fluorescent lights are made. The primary difference is in the glass, 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 visible light in the wavelengths closest to the UV spectrum (indigo 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 fun applications, we must be careful to avoid overexposure, which can lead to increased risk of skin cancer, 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 visible 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 visible 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 fluorescent objects look so cool under a black light.
Black lights have many practical applications beyond simply having fun while bowling, 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.