The Rainbow Lab

This lab explores the physics, mathematics, and geometry of light and optics. It leads the student through a series of questions, experiments, and analysis in order to answer the question ``How are rainbows formed?'' Along the way, students discover why rainbows only occur when the sun is behind the observer, and they predict the angle in the sky that a rainbow should appear if the location of the sun is known. The investigation uses a series of analytical and geometric questions based on a UMAP module by Steven Janke [Janke], but the real visual and numerical power of the lab is its interface to the simulation of light of a given wavelength passing through a spherical water droplet (see Figure 1). The data generated by this simulation intimately connects the physical problem to its mathematical formulation.


Figure 1: Simulation of light rays passing through a water droplet.

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Up: Introduction
Frederick J. Wicklin <>
Last modified: Fri Nov 29 12:28:34 1996