Name: David A.
Is the critical angle for light going from air to water
the same as the critical angle for light going from water to air?
A critical angle exists only for light passing from a slower-speed medium (high index of
refraction) to a faster-speed medium (low index of refraction). When going from water
to air, there is a critical angle: sine of the critical angle equals 1/1.33. When
going from air to water, the sine of the critical angle would have to equal 1.33/1.
Since a sine function cannot be greater than 1, there is no critical angle.
Dr. Ken Mellendorf
Illinois Central College
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Update: June 2012