– How does something hardens just with UV light?

Question

Title, for example teeth fillings or glass glue. How or why is it getting hard / solid just with UV light?

Thanks!

In: Physics

Answer 1

The UV light causes a chemical reaction, which makes the liquid hard.

You can imagine a bit like a photo film. Where the light hit, the film turns dark, as a chemical reaction is happening where the light hit. For your UV hardening polymer, it’s not the color that change, but it turns from liquid to hard if light hits on it.