Measurement of the Speed of Light in Air and Water

Andrew B. Smith, Youngstown State University


The accurate determination of the speed of light holds an essential role in the understanding of the the theory of Special Relativity. This universally consistent speed limit presents difficulty in its determination due to its sheer magnitude. With the use of a Neodymium-doped Yttrium-Aluminum Garnet (Nd:YAG) Laser pulsed by a Q switch, the speed of light is measured in a laboratory traveling first through air and then through a tank of water by measuring the time difference of arrival between two diff erent beams from the initial split laser beam entering an infrared detector, one beam delayed from the other.