What You Need:
- A black light (available at a hardware store)
- Tonic water
- Highlighter pen
- A dark room to do the experiment in
- If you are using a highlighter pen, carefully break it open, remove the felt and soak it in a small amount of water or tonic water for a few minutes.
- Find a dark room.
- Turn on the black light near the water with highlighter ink or a bowlful of tonic water.
The ultra violet (UV) light coming from the black light lamp excites phosphors. Phosphors are special substances that emit light(luminescence) when excited by radiation. Tonic water and the dye from highlighter pens contain phosphors that turn UV light (light we can't see) into visible light (light we can see). That's why the samples created glow in the dark when you shine a black light on them. Tonic water is capable of glowing on its own without the highlighter ink too, due to the presence of a chemical called quinine in tonic water. Black lights are used in forensic science, artistic performances, photography and authentication of banknotes and antiques.