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

Options

A. `(12xx3)/(sqrt(5))`
B. `12xx3xxsqrt5`
C. `(12xx3)/(sqrt(7))`
D. `12xx3xxsqrt7`

Answer

C

Explanation

From fig, tan C=`(r)/(h)`
`r=htanC`

Now, `sinC=(1)/(mu)=(3)/(4)impliestanC=(3)/(sqrt7)`
`therefore r=(12xx3)/(sqrt(7))`