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Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography


Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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 Geometrical Optics
  video  - Polarization of Light
  video  - Polarization of Microwaves
 Polarization by Reflection
 Brewster's angle
 Optical Activity in Corn Syrup
 Polarization by Scattering
 The Eye

Brewster's angle


To demonstrate the Brewster angle at which polarized light is perfect transmitted without reflection.


Set up a laser, polarizer and glass plate on a short optical bench. The glass plate will reflect and refract portions of the incident light. However, when the light is polarized in the same plane as the incident ray and the surface normal, at a certain angle no reflected beam will be observed.

Setup example: you can place a polarizer between laser and glass, set linear polarization to same plane as the glass, rotate the glass until you find minimum (this is Brewster's angle) then remove polarizer from setup. Now you can show that for unpolarized light incident on the glass surface, the reflected light is 100% polarized at Brewster's angle.


One can either use a heavy glass (pivots side to side) and project the reflected light onto the wall/screens or use a microscope slide (pivots up and down) to project on the ceiling.