Speed of Light, Physics 3901, Fall 02

10/4/02

A modulated laser was set up so that the beam went through a beam splitter and reflected off a mirror. The reflected beam from the beam splitter was pointed into one hole on the light sensor. The other beam was reflected off a mirror, and returned to the other hole on the light sensor. A lens with a focal length of approximatel six inches was used to focus the beam into the hole. An ocilloscope was used to read the difference between the two beams. Set at 0.5 volts per division, 820 Hertz, and a time interval of 1 ms, the waves were off by approximately 0.2 divisions. Using the equation given in the lab instructions, and the fact that the total distance traveled by the light was 17.48 meters, our value for the speed of light came out to 6.78 x 10^8 meters per second.

Experimenters: Theresa Crider-Cox, Steve Gerber