< 10 mins
Learn about the action of ultra-violet light.
- Fill one plastic glass with tonic water and one with tap water almost to the brim and label them.
- Place the glasses in direct sunlight. (For best results, do this experiment in the middle of the day.
- Hold a piece of black paper or cloth behind the cups. Look across the surfaces of the tonic water and tap water through the sides of the glasses. You should see a blue glow on the surface of the tonic water (but not the tap water) from the ultra-violet light in sunlight.
When ultra-violet light is absorbed by the quinine in tonic water, it appears again as visible light (the blue fluorescence).
Use sunblock if you do this activity outside on a sunny day.
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How many adults are needed?
Use this calculator to find out the ratio of girls to adults that is required for this activity