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29. mmh A ray of light is
traveling in glass and strikes a glass–liquid interface. The angle of
incidence is 58.0°, and the index of refraction of glass is n = 1.50. (a) What must be the index of
refraction of the liquid so that the direction of the light entering the
liquid is not changed? (b) What is the largest index
of refraction that the liquid can have, so that none of the light is transmitted into the liquid and all of it is reflected
back into the glass? |
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For the direction of light to not be changed, there must not be any refraction. That will happen if there is no change of
index of refraction. Therefore the index of refraction for the liquid must
match the index of the glass. |
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For no light to leave the glass it must be totally internally reflected. So that makes the
critical angle the provided 58.0°. Now we calculate what the index of
refraction needed for the angle of refraction to be
90°. |
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