Problem 2185. Speed of light:Experiment
in 1849, Fizeau set up an experiment to measure the speed of light. The discription of this experiment can be found on wikipedia. http://commons.wikimedia.org/wiki/File:Zahnradmethode_Fizeau.jpg
A animation can be found on http://fr.wikipedia.org/wiki/Appareil_de_Fizeau
L is the source of light
The cogwheel 'Z' has T number of teeth,rotating at X RPM
d is the distance(in km) separating lenses S1 and S2.
Given T, X and d, what was Fizeau's approximation of the speed of light in km/s?
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The units are wrong. d is the distance (in metres) from each lens to the cogwheel (not the distance separating). X is in rps not rpm. The required speed of light is in m/s not km/s.
Aparently the formula used by the author is a multiple of X,T and d divided by 15 for some reason. That doesn't seems to be correct. We should have to convert RPM to angular velocity, distance to metters and use them with a measured time to calculate the speed of light. The required measured time is missing, which was used in the Fizeau's experiment (without it, I don't even see the point of mentioning him or the experiment since we are not replicating its formula, nor his experiment). Finally, the number of teeth is meaningless without knowing more about the cogwheel dimensions.
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