An
air tight chamber 5.0 cm long
with glass windows is placed in one arm of a Michelson
interferometer, as
shown in the figure. Light of wavelength
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Solution: Click For PDF Version Change in phase when air is evacuated from the 5.0 cm long tube, as shown in the figure, will be
where the vacuum wavelength of light used in the experiment is
It is
observed that when the tube is evacuated 60 fringes are observed to
pass through the view. For a change of phase of
We thus have the relation
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is used. The
air is slowly evacuated from the chamber using a vacuum pump. While
the air is being removed, 60 fringes
are observed to pass through the view. From
these data, we have to
find the index of refraction of air at atmospheric pressure.
.
a fringe is shifted by another fringe. We therefore have
