Question

A fish looking up through the water sees that the outside world is contained in a circular horizon. If the refractive index of water is 4/3 and the fish is 12cm below the surface of the water what is the radius of the circle?

Answer 1

After makig the figure U would get the final relation as

tanthetha = r/h

where thetha is the angle making with height h (perpendicular and the hypertenuse.)

and this angle is also the TIR angle.

Therfore from,

sinthetha = 1/u = ¾

thanthetha = 3/root(7)

and r = 36/root(7)