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PHY 202
Your 'question form' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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Problem Set 6 #22 and 24
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Specifically, problem #22 in Set 6, at http://vhmthphy.vhcc.edu/ph2introsets/set_6/zpb22a6.htm
(though I think the actual problem will be different when you access it tomorrow).
Also, problem #24 in Set 6, at http://vhmthphy.vhcc.edu/ph2introsets/set_6/zpb24a2.htm
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For #22:
dImg = f * dObj / (dObj + f) = 6 m * 5 m / ( 6 m + 5 m) = 0 meters
Is this an error? The solution goes on to use the 0m answer in further equations and in the explanation, but I think this is a mistake?
For #24:
The solution uses the following equation:
sin(`thetaRef) / sin(`thetaIn) = n2 / n1
Yet #23 uses:
sin(`thetaRef) / sin(`thetaIn) = n1 / n2
Is there a reason for this that I am missing or is this just an error?
Thank you in advance!
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That's an error. If n2 is the index of refraction in the second material, the refracted angle is in that material. A greater value of n2 implies more refraction so that the ray is 'closer' to the normal direction (the direction perpendicular to the interface between the two materials), which implies a lesser angle of refraction.
Since the sine of an angle increases with the angle, this implies a lesser value of the sine in the second material.
It follows that n2 will be in the denominator when sin(thetaRef) is in the numerator.
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Of course none of this proves Snell's Law, it's just a commonsense way of remembering that the index of refraction and the corresponding angle are in opposite parts of the two fractions.
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