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Critical Angle

by ZxcvbnM2000
Tags: angle, critical
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May1-12, 12:08 PM
P: 64
Snell's Law of Angles says that : sinA/sinB = nB/nA

but in order to find critical angles B has to be 90 . I understand that in order to have total internal reflection that nB/nA < 1 but why can't there be a CRITICAL angle when nB/nA > 1 ?

sinA would have to be greater than 1 which cannot happen but if i do it separately : glass to air and water to air and say that air-n-water = nwater/nair it is 1.33/1.5 which is true but if i do it in one go it is 1.5 / 1.33 . I must be doing something wrong , because this seems too easy :S
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May1-12, 06:20 PM
Drakkith's Avatar
P: 11,878
What do you mean by "if i do it in one go"?

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