We present an update of the “refractive index of air” experiment, which is commonly used in undergraduate advanced laboratories. The refractive index of air depends on the average molecular polarizability, which can be determined from the period of the phase shift in a Michelson interferometer as a function of air pressure. The measured average molecular polarizability of air is (95% CI). The corresponding refractive index of air at atmospheric pressure is , which agrees with the accepted value of .
REFERENCES
1.
Instruction Manual and Experiment Guide for PASCO Scientific Michelson Interferometer, Model OS-8501, pp.
12
–14
.2.
M. A.
Jeppesen
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John David
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It is common to denote the number density as . However, since we use for the refractive index, we will use to represent the number density.
8.
Bengt
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Philip E.
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NIST Electromagnetic Toolbox, Modified Edlén equation calculator, ⟨http://emtoolbox.nist.gov/Wavelength/Edlen.asp⟩.
11.
PASCO precision interferometer OS-9255A.
12.
PASCO light detector CI-6504A.
13.
Vernier gas pressure sensor GPS-BTA.
14.
For example, Vernier software, “LOGGER PRO,” information available at ⟨http://www.vernier.com/soft/lp.html⟩.
© 2011 American Association of Physics Teachers.
2011
American Association of Physics Teachers
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