Do you have any predictions? With three bottles of water, one bottle filled with water mixed with highlighter dye, one bottle filled with tonic water, and one bottle filled with regular tap water, which ones do you think will glow?
Borrow a black light, get your supplies together, and give this simple and fun science experiment a try! We have a supplies list, printable instructions as well as a demonstration video with experiment explanation below. Explore phosphors and have fun while learning!
- 3 Empty Bottles or Drinking Glasses
- Tonic Water
- Black light
Step 1 – Prepare the water for the first bottle. To do so, pull the back off a highlighter and drop the ink into a cup of water. Set aside.
Step 2 – Prepare the water for the second bottle. Do this by filling the second bottle with tonic water.
Helpful Tip: If you buy tonic water that is already is a clear glass jar, you can just use that.
Step 3 – Prepare the water for the third bottle. Do this by filling the third bottle with regular tap water.
Step 4 – Take the water with the highlighter ink in it that you prepared in step one. Sir the water to mix in the ink and then pour it into the first bottle.
Step 5 – Position the black light behind the bottles.
Step 6 – Turn on the black light and observe the three bottles. Do any of them glow? Do you know why? Find out the answer in the how does this experiment work section below.
The bottle with regular tap water does not glow when placed near a black light.
The bottle with water and highlighter dye and the bottle with tonic water do glow when placed near a black light. This is because highlighter dye and a chemical found in tonic water called quinine contain something called phosphors. Phosphors are substances that emit light (or luminesce) when exposed to radiation like UV light. When you shine a UV light on phosphors, the phosphors become “excited” and glow. Your teeth and fingernails also contain phosphors so they will also glow in UV light!
I hope you enjoyed the experiment. Here are some printable instructions: