Michelson experiment for measuring the speed of light

Michelson Experiment

How did the Experiment Came About the idea of measuring the speed of light, in a more exact and accurate result, was brought about to Albert Michelson during his teaching years at the Naval Academy. During his physics and chemistry class in the academy, when requested by Sampson, his Lieutenant Commander, to provide a demonstration of measuring the speed of light using Foucault's theory, the idea of creating an apparatus for measuring the speed of light with greater accuracy came about to Michelson while assembling Foucault's speed of light measuring apparatus.

The academy unfortunately didn't have enough money to support Michelson's experiment. Asking for his father-in-law's support, Michelson was able to get $2,000 to carry out his study and experiment (Fowler, 1996). He spent money for good quality mirrors and lenses that he used in his experiment. Michelson conducted his experiment in several places due to some factors that he believed to have affected the accuracy of his calculation. Soon, his test was successfully completed in a 2000 feet distance, as compared to Foucault's 60, in the Irvine Ranch.

As a result of Michelson's experiment in measuring the speed of light, the Optics Institute of Southern California online indicates the following.

186,282.3960 miles per second, plus or minus 3.6 feet per second

299,792.4562 kilometers per second, plus or minus 1.1 meters per second

And, following is the diagram of Michelson's experiment as well as the real speed of light measuring device that he built, as shown by the Optics Institute of Southern California Online.

The above diagram shows how the speed of light is measured by Michelson using mirrors where a beam of light is assumed to bounce to every mirror and bounce back to its source.

The Speed of Light

Michelson discovered from his experiment that light travels at a constant speed and that the movement of the earth does not affect its speed in any way (MJ Lea).

In his experiment, Michelson used flat mirrors and concave mirrors where his objective is to measure how much time will a beam of light travel from its source, bouncing to a mirror, and to another mirror, and bounce back to its source. Newton online explains this further as follows.

Albert Michelson measured the speed of light by measuring the time it took for a beam of light to hit a mirror on one facet of an octagonal rotating mirror, bounce to a mirror on a mountain 35 km away and then back to his octagonal mirror. If he adjusted the rate of rotation correctly he could be sure that the light upon returning to his lab hit the same mirror.

Michelson was able to calculate the speed of light from the speed of rotation of the wheel of a device at the center of a metal shack that he built, the distance that the light had traveled, and the angle of the light beam as it bounces back and forth through the mirrors (the Optics Institute of Southern California).