University of Edinburgh

BSL Physics Glossary - fluorescence - definition

We can't see UV light, but when UV light reaches a surface or a certain material, the UV radiation is absorbed, and the material glows, so it becomes visible. This property of fluorescence is used in shops that want to check that a high value note, like a £50 note, is real. The shop assistant puts the note under a special UV lamp behind the counter. If it glows, then it's a genuine note, not a forgery. Sometimes if you go to parties or clubs you see a light which looks purple or blue. It's a UV light. It makes everything white fluoresce, like your shirt or your teeth.