Feature

Optics for the Fish

R. John Koshel

Helping students understand physical phenomena can be rather difficult at times. Everyone sees optical effects in the real world—reflections in a car's rear-view mirror, scattering making the sky blue, diffraction of street lights through a window screen, and Moiré fringes in household curtains. Many of these effects go unnoticed and are hard to bring into the lecture hall. I have developed a series of experiments using a water-filled fish tank to display principles of optics such as refraction, reflection, scattering, and interference, as well as demonstrate a simple water-based system for optical communication.