Malus experiment: Polarization by reflection off glass surface.

6H20.20 • E+45+10

Malus experiment: Polarization by reflection off glass surface. Ref: Modern College Physics by Harvey White, 6th ed., p.610-611 In this demo, ordinary white light hits one glass plate at the polarizing angle 57 deg , then hits a second parallel glass plate at 57 deg . The second plate is slowly rotated, and the reflected spot is bright (0 deg ), then becomes dimmer, then vanishes (90 deg ), then becomes a bright maximum again (180 deg ), and so forth. In 1808, Etienne Malus discovered that when light is incident on polished glass at an angle of 57 deg , the reflected light is plane polarized. In this setup, light from a slide projector hits glass plate 'A' at 57 deg . The refracted portion of the beam goes into the glass and is absorbed by black paint; the reflected portion of the beam is plane polarized and hits the center of glass plate 'B' also at 57 deg . Plate 'B' serves as an analyzer for polarized light: a portion of the incident light is reflected when the waves are perpendicular to the plane of incidence. But the incident light is refracted (and absorbed) when the waves are parallel to the plane of incidence.