Imagine a large number of of parallel rays hitting a spherical

rain drop. For each ray we plot a single point of light in accordance

with the laws of

randomly choose a color that will be seen by an observer once it has

been refracted & reflected either resulting in a point of light in

the primary or secondary rainbow. Since we are randomly assigning a

color from the spectrum to a ray, the process is using a Monte Carlo

simulation. In order to get the angles correct we use the refraction

index of the colored light for the mediums air and water. This also

determines the placement of the corresponding dot of light in our picture.

The crucial line of code is the expression for N. By changing this

line we can simulate rainbows in various mediums.

(If no input is specified 10,000 are used.)

Donald Olsen, et al., The Physics Teacher, April 1990, pp. 226-227

This was the result of an NSF summer program involving eighth and ninth

grade students. The original program was written in Applesoft Basic.

David R. Hill, Mathematics Dept., Temple Univ.

Philadelphia, PA. 19122 Email: dhill001@temple.edu

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CONSTRUCTED for use with NSF Project DEMOs with POSITIVE IMPACT

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