Question: when oil comes out a car why does a rainbow form on the ground

Jess Wade answered on 19 Jun 2015:

Hey charley
This is all about clever ticks of light. Light travels in straight lines, and when it hits different materials or molecules it starts to wiggle all of their electrons (gives them lots of energy) and wastes some of its energy. Because it is giving them the energy, the light slows down. When light slows down it starts to bend. When light bends it changes colour. The light hits the top surface of the oil, bends a bit, then hits the ground below the oil. Some light just hits the surface of the oil. There are now two rays of light, one that comes from the water and one that comes from the surface and just bounces off. These two light waves start to interact with each other. sometimes they are both glowing in the same way and shine brightly. Sometimes they aren’t :(. This gives us bright and dark spots of colourful light.