New Orleans:

January, 13 => 1.45 pm


Exploring the Theory of the Rainbow

I will present two teaching aids, which can help students explore the mathematical theory of the rainbow. An interactive computer demo (in Cabri) enables the student to investigate the path of rays of light in a raindrop for different indices of refraction. Then the student can experiment with a spotlight, a cardboard screen and a spherical bottle filled with water as a three-dimensional model of the raindrop. This experiment is based on an idea of Marcel G. Minnaert (1893-1970) of Utrecht. From here it is a small step to the explanation of the rainbow. The teaching aids are part of my M.Sc. work in mathematics education, and they can be used at early undergraduate level and in the mathematics and physics curriculum of the final year of the Dutch highschools.

The Ten-Minutes-Talk

The text: text.pdf


Sheet of the raindrop: sheet1.pdf

Sheet of the angle: sheet2.pdf

Sheet of the maximum of the angle (arcsin): sheet2a.pdf + arcsin.pdf

Sheet of some path of rays of light in a raindrop: sheet3.pdf | sheet3a.pdf

Applet of the raindrop: applet1

Applet of the angle: applet2


Photo's of the experiment tools: sheet1.jpg

Another photo of the experiment tools and a close-up of the spectrum: sheet2.jpg

Photo's of the first place of braking the rays of light: sheet3.jpg

Photo's of the second place of braking the rays of light: sheet4.jpg

Photo's of the third place of braking the rays of light: sheet5.jpg