Sam is sitting in her fishing boat watching a trout swim below the surface. She guesses the apparent depth of the trout at 2.0m. She estimates that her eyes are about 1.0 m above the water's surface, and that the angle at which she's observing the trout is 45 degrees.

Question

a) draw a diagram t show the ACTUAL depth of the trout and the path of light from the trout to Sam's eyes
b) Calculate the actual depth of the trout

Answer 1

You have to remember that in the air, the light from the fish is bent away from the normal.

See Snell's law. Use your diagram to calculate the depth, using trig.

Answer 2

Bob - thanks for the reply. I have figured out the angle of incidence to be 32.3 degrees, but do not know how to caluclate the depth as underwater heigh is given (the only heigh is 1 m above water which I don't think i useful)...can you please help me more.

Answer 3

* I meant, NO underwater height is given

Answer 4

It says "it looks" like the fish is 2 meters deep.
Draw a straight line from the eye to the water, hitting at 45 degrees.
Continue the straight line (ignoring Snell's Law below the water until it is 2 meters under.
Now go back and do the correct angle in the water from the point where the line hit the water.
The fish is on that line and a vertical line through the point where it "looked like" the fish was.

Answer 5

I figured out the angle to be 32 degrees but still don't know how to figure out the height...