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30 January 2004

A Simple Bubble Reflection Viewer

By Greg Randall

Recently I set up a very simple bubble reflection viewer by taping a piece of thin paper over a desk lamp to form a light diffuser. I dipped a coat hanger bent into a rectangle in bubble liquid and put it in front of the lamp.This diagram shows the exact setup (from the top):

 

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You can best see the reflections from the bubble when angle A and angle B are equal. Here is an example:

 

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Basically what happens is this: The bubble's thickness changes (because of wind or sagging of the liquid film that forms the bubble) so the light reflects and refracts at different times. This creates constructive and destructive interference and changes the color of light reflected by the bubble.

For a really good explanation go here

http://www.exploratorium.edu/ronh/bubbles/bubble_colors.html.