Brewster's Angle - Semicircular Lucite Slab

Purpose

To demonstrate polarization at Brewster's angle.

Equipment

Bright point source, mounted semicircular plastic slab, protractor, and polarizing sheet.

Setup Time

5 min

Images

m7-13

Description

A light ray from a bright point source with a condenser lens and iris is incident on a semicircular lucite slab through the curved surface. Using the protractor the Brewster angle is found by rotating the slab until the angle between the refracted ray and the ray internally reflected off the flat surface is 90 degrees. Inserting a polaroid in the incident light ray verifies that the internally reflected ray is polarized in the vertical plane.