Quickly and confidently demonstrate the concept of wave interference. Stack two identical circle patterns together on an overhead projector. Slowly slide one pattern over the other and the interference pattern will clearly develop before your eyes. Then, measure the angles of the interference bands to confirm the relationship between wavelength and slit separation. Repeat the demonstration using the larger-spaced circles to show how the interference pattern is affected by “wavelength.” Circle Pattern Masters are provided and can be photocopied onto transparency paper for students to follow along with the demonstration at their desks. Includes complete demonstration instructions.
Concepts: Interference pattern, wavelength, coherent light, diffraction. Time Required: 15 minutes Materials Provided: Two pairs of circle patterns silk-screened on durable acrylic plates, protractor transparency sheet, master copies of each circle pattern and protractor sheet. Note: Requires an overhead projector. Student transparency paper is not provided.