PURPOSE: To demonstrate polarization of an internally reflected light beam, and to demonstrate Brewster's angle.
DESCRIPTION: A single ray of light enters a semicircular plastic slab and is reflected and refracted by the internal flat surface. Brewster's angle is the angle at which the internally reflected ray is completely polarized in the plane perpendicular to the optical board surface. This occurs when the angle between the refracted and the internally reflected rays is exactly 90 degrees. This can be verified by rotating a polaroid sheet in the light ray coming from the source at the left. Note that the refracted ray is partially polarized at this angle.
The lens is used to keep the light ray to a minimum size. Use of the semicircle assures that the incoming and reflected rays will enter and exit normal to the surface and experience no bending.
REFERENCES: (PIRA 6H20.10)
EQUIPMENT: Optical board with semicircular plastic slab, single ray baffle.
SETUP TIME: None.
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