Major ideas
1. The speed of light is a fundamental physical constant which is ubiquitous in all manner of phenomena and applications; electricity and magnetism, special and general relativity, gravity waves, stellar aberration, laser ranging, time standards, communications technology, etc. etc. etc. Therefore, knowing the speed of light is crucial to interpreting these phenomena and designing devices that depend on the speed of light.
2. The invariance of the speed of light is the cornerstone of Einstein’s Special Theory of Relativity (1905).
Major equipment
1. A high speed rotating mirror is the key to the Foucault Method (1862) for measuring the speed of light. The rotating mirror can rotate up to1,500 rev/s. What is the role of the rotating mirror?
2. A measuring microscope (equipped with cross-hair sight and micrometer adjustment mechanism) is crucial for measuring the displacement of the image point. How does the micrometer work? What is the precision of the micrometer?
Data analysis
1. Error propagation – How do the uncertainties in each measurement made affect your final result for the speed of light. There are seven separate numbers (A, D, B, s’cw, s’ccw, ωcw, and ωccw) used in finding the speed of light; see page 15 of the Pasco manual. What is the percentage/fractional uncertainty in your final result for the speed of light?
2. Which measurement, of the seven, has the largest effect on the uncertainly of the speed of light. That is, if you were to redesign this experiment which measurement would you refine first to get a smaller overall uncertainty?
For a detailed guide to the experiment see the attached documents below.
Bates, H. E. (1988), "Resource Letter RMSL-1: Recent measurements of the speed of light and the redefinition of the meter," Am. J. Phys. 56, 682; doi: 10.1119/1.15500