Unit: Waves
Year: 1989 Question#: 50
Question: Total internal reflection can occur as light waves pass from
(1 ) water to air
(2 ) lucite to crown glass
(3 ) alcohol to glycerol
(4 ) air to crown glass
What is this question really asking?
Explanation by: Yui H.
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Answer 1
water to air
correct
This answer is correct because water is slower medium than air and when light enters faster medium from slower medium, it will bend away from the normal. Total internal reflection can occur when incident angle is greater than the critical angle.
This diagram shows the light hitting air but incident angle is equal to the critical
angle, so the light is reflected (total internal reflection)
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Answer 2
lucite to crown glass
incorrect
This answer is incorrect because lucite is faster medium than crown glass. Light will bend towards the normal which means away from the medium.
This diagram shows light that is going out is refracted. The incident angle is greater
than the angle after exiting the medium.
return to top Answer 3
alcohol to glycerol
incorrect
This answer is incorrect because alcohol is faster medium than glycerol. Light will bend towards the normal which means away from the medium.
This diagram shows light that is going out is refracted. The incident angle is greater
than the angle after exiting the medium.
return to top Answer 4
air to crown glass
incorrect
This answer is incorrect because air is faster medium than crown glass. Light will bend towards the normal which means away from the medium.
This diagram shows light that is going out is refracted. The incident angle is greater
than the angle after exiting the medium.
return to top What's this question really asking?
When can the total internal reflection occur? return to top
