Complete Speed of Light Apparatus

Product Code: OS-9261B


The Speed of Light Apparatus uses the “Foucault Method” to accurately measure the speed of light.

How It Works

The Foucault Method:

  1. The first observation is made when the rotating mirror is not rotating. Light from a He-Ne laser is reflected from the rotating mirror and focused onto the fixed mirror. The fixed mirror reflects the image back onto the rotating mirror, which in turn reflects the light back through the lenses to reform the image, where it can be observed with the microscope.
  2. The second observation is made when the rotating mirror is rotating. Since it takes a finite amount of time for the light to traverse the distance between the fixed and rotating mirrors, the rotating mirror is in a slightly different position when the light returns after reflecting off the fixed mirror. This produces a displacement, which can be measured with the microscope.
  3. The displacement between the first and second observations is proportional to the transit time of the light to the angular velocity of the rotating mirror. With a very straightforward calculation, the speed of light can be calculated.

What’s Included

  • 1x 1 m Optics Bench
  • 1x Laser Alignment Bench
  • 1x Mini Laser with Bracket
  • 1x Double Convex Lens, 48 mm F.L.
  • 1x Plano Convex Lens, 252 mm F.L.
  • 1x Calibrated Polarizer
  • 1x Component Carrier

Buying Guide

Parts Available Separately P/N
Laser Alignment Bench — Advanced Optics OS-9172
Mini Laser with Bracket OS-8514
Speed of Light Experiment EX-9932A

Support Documents

Complete Speed of Light Apparatus Manual

Speed of Light Apparatus Manual