Speed of Light Experiment

Product Code: EX-9932A


The Speed of Light Experiment uses laser light and a high speed rotating mirror to determine this fundamental constant using the Foucault method.

Laser light passes through a series of lenses to produce an image of the light source at a measured position. The light is then directed to a rotating mirror, which reflects the light to a fixed mirror at a known distance from the rotating mirror. The laser light is reflected back through its original path and a new image is formed at a slightly different position. The difference between final/initial positions, angular velocity of the rotating mirror, and distance traveled by the light are then used to calculate the speed of light in air.

PASCO Advantage: PASCO’s Speed of Light Experiment allows students to experimentally measure the speed of light within 5% of the accepted value. In addition, the experiment can be performed on a desktop or in a hallway.


  • Determine the Speed of Light in Air
  • Recreate Foucault’s Historical Experiment


Speed of Light Experiment

What’s Included

Manual Downloads

Product Manuals for the Included Products

Helium Neon Laser 0.5 mW Manual (OS-9171)
(47 KB – .pdf – English)
OS-8514 instruction sheet
(48 KB – .pdf – English)
Experiment File
Speed of Light Experiment File
(961 KB – .zip – English)