Speed of Light Experiment - 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.

This experiment is available for Download at no additional cost.



  • Complete Speed of Light Apparatus (OS-9261B)
  • Speed of Light Experiment Manual