Review: Color Addition Spotlights do everything that the three-projector set up can do (described in this issue) in a more efficient way. The spots fit in a base that holds them securely but allows you to aim them to create three circles of light overlapped in whatever pattern you wish. The kit contains primary and secondary color filters ($125.00). An optional control box has dimmer switches ($61.00).
Other Information: Arbor Scientific, PO Box 2750, Ann Arbor, MI 48106-2750. Call 800-367-6695, online at http://www.arborsci.com.
The first part of this article describes the concept of light propagation in straight lines. The second section discusses light dispersion. The activities and everyday examples that follow each section will help students construct these fundamental concepts and, hopefully, appreciate their power in unifying a rather diverse set of phenomena.