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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  - Interference and Diffraction
 Arago's (Poisson's) Spot
 Razor Edge Diffraction
 The Eye

Razor Edge Diffraction


To demonstrate the diffraction on the edge.


The setup is shown in the picture below. The laser is on a horizontally adjustable mount. Put out the lights and point out the laser dot on the screen. Slowly turn the laser so the beam intersects the edge of the razor blade. Diffraction lines can be seen as the light "bends" around the razor's edge.


The razor edge and the Poisson spot are on the same mount.
In room 203 use a regular camera and #4 light setup to project the diffraction pattern on the big screen.


  • 18.8 cm Lens and stand
  • Optical Stand
  • Razor Blade
  • Helium Neon Laser