Physics at the University of Virginia
Academics People Research Announcements Facilities Adminstration Home Updates

Return to Demo Lab Homepage

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.

Choose a Topic or Enter a keyword to search:
I cannot find what I want!

You have selected the following Demos:
  • None Selected

Choose a subtopic:
(Clicking a green button will add that demo to your list)
 Geometrical Optics
  video  - Interference and Diffraction
 Arago's (Poisson's) Spot
 Razor Edge Diffraction
 The Eye

 video  - Interference and Diffraction


Shine a laser beam through single, double and multiple slits of different widths and spacing on a Cornell multiple slit film.


centered image
centered image
  Apparatus Introduction - DEMO VIDEO DOWNLOAD - HD - 1920x1080 / 27.4Mbps - 224MB size  

  Apparatus Introduction - DEMO VIDEO DOWNLOAD - LD - 854x480 / 5.69Mbps - 56MB size  

centered image
  Diffraction - DEMO VIDEO DOWNLOAD - HD - 1920x1080 / 27.4Mbps - 186MB size  

  Diffraction - DEMO VIDEO DOWNLOAD - LD - 854x480 / 5.69Mbps - 40MB size  

centered image
  Interference - DEMO VIDEO DOWNLOAD - HD - 1920x1080 / 27.4Mbps - 271MB size  

  Interference - DEMO VIDEO DOWNLOAD - LD - 854x480 / 5.69Mbps - 55MB size  

Set the stand so that the different patterns can be projected onto a wall or screen. The film holder can be moved in X & Y and secured by two thumbscrews to hold different patterns steady. On the film there are four different columns of slits. The first of these is a series of single slits varying in width. The second is a continuously varying single slit that gradually resolves itself into a varying double slit. The third and fourth sets are of multiple slits of various spacings. The middle pattern in the third row has the most slits, thus giving the sharpest interference pattern. The fifth is a series of double slits of the same width that vary only in their spacing.


  • It is best to use the apparatus at the back of any of the rooms, and shine the diffracted or interfered laser light onto the projector screen. Best to use projector room in for Rm. 203.
  • By request a red or green laser can be used. The green laser is brighter and can be used w/out dimming the room's lights but is very noisy. The old red laser needs ceiling lights off but the contrast for the minima and maxima for closely spaced patterns is better.


  • 1 0.95 mW He-Ne laser
  • Cornell slit film
  • laser stand