A good place to begin exploration of interference is by creating an interference pattern by shining a laser beam through two slits. We do this at the exhibit "Interference Patterns." In the classroom you can duplicate this exhibit:

Interference Laser

You can then model what is happening with the Exploration

Two Slit Interference Model

A beautiful activity to inspire exploration of the colors of soap films is to make soap films, this is easy to do by making the soap film across the mouth of a black plastic film can 

Soap Film in a can

After exploring the colors of soap films we can look at how waves reflected from the front and back of a soap film add together to cancel some wavelengths of light and enhance others.

Soap Film Interference

At last we can put together all of the colors that are reflected from the soap film to create the color that we see by eye.

Soap Film Color

By doing all of these activities you can gain an understanding of how soap films become colored even though the soap films themselves are transparent.

You can also apply what you have learned in the above activities to explore the colors of oil films on water.

Or even to explore air films between two pieces of plastic or glass with the Bridge Light Snack.

Explore diffraction with a minimag light at the Diffraction Snack.

Do a quantitative version of the two slit interference in the Math Root: interference.

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Scientific Explorations with Paul Doherty

© 1999

24 May 2000