Refraction and Prisms

Main Question or Discussion Point

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That is a page from my textbook. The book mentions that the angle of incidence on the right side when added with the angle of the refraction equals 60 degrees. Why is that?
 

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Consider the triangle formed by the light ray in the prism and the two prism borders. The sum of the interior angles is 180°, and one angle is 60°. Everything else follows from geometry with the right angles there.
 
Which triangle? If you mean the one formed by the refracted ray, it is not a right angle triangle.
 
blue_leaf77
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Triangle ABC:
$$
\angle A + \angle B + \angle C = 180^0
$$
Or triangle formed by B, C, and the prism's apex.
 

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sophiecentaur
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Another way to look at it. The very top triangle has one angle of 60°. The other two angles are 90- i and 90-r etc. etc.....
 
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Another way to look at it. The very top triangle has one angle of 60°. The other two angles are 90- i and 90-r etc. etc.....
That is the triangle I meant.
And the sum of those three angles is 180 degrees.
 

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