A
coin lies at the bottom of a pool with depth d and index of
refraction n; as shown
in the figure. We have
to show that light rays that are close to the normal appear to come
from a point
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Solution: Click For PDF Version As shown in the figure, we view the coin from air close to the normal. Therefore, the angle of incidence
is small and we use the small angle approximation
From Snell’s
law we find the angle of refraction
In the small angle approximation, we have
where n is the index of refraction of water with respect to air. As the depth of the pond is d, we note
This gives that
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below the surface. This
distance is called the apparent depth of the pool.
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