Make glowing water with the help of a black light in this fun science experiment for kids. Tonic water doesn’t look very strange under normal light but what happens when you look at it under a black light? Does the dye from a highlighter pen do the same thing? Find out what happens and why it happens with this cool experiment that you can do at home.
A black light lamp, Tonic water or a highlighter pen and A dark room to do the experiment.
If you are using a highlighter pen, carefully break it open, remove the felt and soak it in a small amount of water for a few minutes.
Find a dark room.
Turn on the black light near your water. How does it look?
The ultraviolet (UV) light coming from your black light lamp excites the things called phosphors. Tonic water and the dye from the highlighter pens contain phosphors that turn the UV light (light we can’t see) into visible light (light we can see). That’s why your water glows in the dark when you a black light on it.
Black lights are used in forensic science, artistic performances, photography, authentication of banknotes and antiques, and in many other areas.
Black light (also known as the UV or the ultraviolet light) is a part of the electromagnetic spectrum. The electromagnetic spectrum also includes infrared, X-rays, visible light (what the human eye can see) and other types of electromagnetic radiation. A black light lamp, such as the one you used, emits a UV light that can illuminate objects and materials that contain phosphors. Phosphors are special substances that emit light (luminescence) when excited by radiation. Your water glowed under the black light because it contained phosphors. If you had used a highlighter pen, then the UV light would have reacted with the phosphors in the dye. If you had used tonic water, then the UV light reacted with the phosphors in the chemical used in tonic water called quinine.
There are different types of luminescence. These include fluorescence (used in this experiment, it glows only when the black light is on), phosphorescence (similar to fluorescence but with a glow that can last even after the black light is turned off), chemiluminescence (used to create glow sticks), bioluminescence (from living organisms) and many others.
