The Speed of Light
The speed of light as a wave speed is related to its frequency ( ?) and its wavelength ( l );
c =
¦l. The speed of light was formally determined experimentally by the International Committee on Weights and Measurements to be c = 2.99792458 ?108 m/s.
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Michelson used two concave mirrors, with distance d, and an octagonal mirror, rotating with
period T. The light source was reflected by one side of the octagonal mirror, made a round trip back and was reflected by the next side to the observer. The speed of light c was then found to be c = 2d / ( T/ 8 ) = 16 d / T.