Polaroids And Gooseneck Lamp

Purpose

To demonstrate polarization of light.

Equipment

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

Images

m7-03

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).