A tabletop experiment for the direct measurement of the speed of light

Abstract

A small tabletop experiment for a direct measurement of the speed of light to an accuracy of few percent is described. The experiment is accessible to a wide spectrum of undergraduate students, in particular to students not majoring in science or engineering. The experiment may further include a measurement of the index of refraction of a sample. Details of the setup and equipment are given. Results and limitations of the experiment are analyzed, partly based on our experience in employing the experiment in our student laboratories. Safety considerations are also discussed. *

An educational physics laboratory experiment for directly measuring the speed of light

“…The accuracy of the method is determined by the resolution of the method of measuring the time delay, which is estimated at ~ 1 ns. This accuracy meets the requirements for school experiment and is of the same order as the accuracy achieved by Aoki et al (2008).…”

“…The speed of light was estimated with a great mistake (25%) that was mainly due to the bad accuracy in the estimation of the Earth's orbit; even so, it became a well known fact -the speed of light is about several hundred thousand kilometers per second. Cooke et al (1968), and by Aoki et al (2008), although relatively imprecise in comparison with the interference methods (see James et al, 1999), enables direct measurement of the speed of light in the university/school physics laboratory. In the standard optical location methods the distance is determined by knowing the light velocity and measuring the time that it takes to the optical signal to travel along the distance.…”

A preliminary investigation to decipher an enigma using time-of-flight sensor

“…[8] Laser meter has been used to ascertain RI. [9] Time-of-flight (TOF) LiDAR has a laser emitter and single photon avalanche diode (SPAD). SPAD is an avalanche photon diode, which is biased higher than the breakdown voltage.…”

An extraordinary tabletop speed of light apparatus

“…Judging from the large number of papers that have been published in this journal, the methods for the determination of c in free propagation are of great interest. These different approaches can be classified into four categories: modulation methods; [1][2][3][4] pulse methods for the measure of time of flight, [5][6][7][8][9][10][11] with the special category of pulse methods that use the structure of longitudinal modes of laser cavities; [12][13][14] new versions of classical methods such as Foucault's rotating mirror; 15,16 and finally methods that rely on interference effects or electrical pulses. This last category includes, for instance, the propagation time of electrical pulses in coaxial cables, 17,18 the interference of microwaves, 19 electromagnetic waves generated by a microwave oven by measuring the length of the modes in the cavity or extracting some energy and using Lecher lines, 20 the reflection of TV radio waves by distant obstacles, [21][22][23] and even the time of propagation of Ethernet packets in a cable connecting two computers.…”