Question: Hi, why do bubbles have multi-colours in them? What does the light do to the bubbles to cause that?

Rowena Fletcher-Wood answered on 14 Mar 2014:

Bubbles consist of thin films of surfactants (soaps). The bubble film has two surfaces, an inner and an outer surface. The colours form when light interacts with both surfaces. When it meets one some light is reflected and scatters off the curved surface and some passes through and then diffracted at the other surface – like with a prism. This creates all kinds of pretty colours over the surfaces of the curved films. 🙂