Interference by thin films


Have you ever looked at a spot in a parking lot where oil dripping from a leaky car has created a shallow puddle?


This image of an oil slick is Copyright 2005 Jeff Wignall, and is reproduced from an Instructor Insights column on betterphoto.com

Have you ever noticed the intense colors of a butterfly's wing?


Image by Dystopian Optimist licensed under Creative Commons .

These are examples of iridescence, the color produced when sunlight strikes a very thin film of material.