One bright summer day a swimmer is floating with her head just above the surface of a large, clear lake where the water has index of refraction n = 1.43. She comes upon a tall wooden post emerging from the water. When she looks into the water at just the right angle she can see the bottom of the post, which is at a depth h = 5.50 m below the water's surface. As she floats away from the post, eventually she can no longer see the bottom of it. At what distance d from the post does this occur? (in m)

5.38035 m

Explanation:

= Refactive index of water = 1.43

h = Depth = 5.5 m

Critical angle is given by

d = horizontal distance from the post where she no longer see the bottom of wooden post

So,

The distance d is 5.38035 m

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hope this : )