Is there any difference between the colours emerging from a prism and the colours of a soap film seen in sunlight?

Answer 1

No. In soap bubbles the color you see is proportional to the thickness of the soap bubble, and not the angle. This is because in a soap bubble, the light you see is the sum of the light reflecting off of the outer surface and the inner surface, which cancel out and add to get various colors, whereas in a prism, light is simply reflected and dispersed at an angle based on its energy.

The way they reflect on the inner surface and outer surface is different at different thicknesses of bubble. Waves that travel from air to water have their peaks become troughs and vice versa. Really thin bubbles do not reflect at all and appear black against a black background. This is because the wave bouncing off of the back side of the bubble cancels out with the one bouncing off of the front. Different thicknesses cancel out some frequencies while leaving others (for example a 200 micrometer bubble cancels out blue and leaves orange because the wavelength of blue light is just right to be canceled).

Another interesting thing is that, since waves are periodic (repeat up and down) , a bubble with twice the thickness will cancel out the wave in the same way. So if you graph bubble thickness vs. color of bubble, you will get roygbiv roygbiv ... over and over.