M7-03. Polaroids And Gooseneck Lamp

Purpose

To demonstrate polarization of light.

Equipment

Goose neck lamp, large round polaroids on base, extra square polaroid.

Images

Description

The first polaroid polarizes the light. Rotating the front polaroid causes the light to become alternately brighter (polaroids aligned) and dimmer (polaroids crossed). Insert a third polaroid between the two crossed polaroids at a 45 degree angle to show that the electric field is a vector, and to demonstrate a component of a component. Argue with your students about what happens in this experiment when the light passes one photon at a time.

References

Hollis N. Todd, Polarization of Light - Basic Theory and Experiment, Bausch & Lomb Inc. (1970). H. Richard Crane, How Things Work: How Does the Honeybee Sense Polarization?, TPT 27, 504-505 (1989).