A
ray of light is incident normally on the face ab of a glass prism
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Solution: Click For PDF Version Let n be the index of refraction of the glass prism and
be that of the outside medium in which the prism is kept.For total internal reflection to take place, it is necessary that
The critical
angle for total reflection
And this
angle fixes the largest value of the prism angle
(a) When the prism is kept in air, we have
(b)
When the
prism is immersed in water
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,
as shown in the figure.
(a) Assuming that the prism is immersed in
air, we have to find the largest value for the angle
so that the ray is totally reflected at the face;
(f) we have to find
.
is determined by the condition
for the incident light to get refracted along the edge of the prism,
as shown in the figure. We have
.