A fish looking from within water sees the outside world through a circular horizon. If the fish `sqrt(7)` cm below the surface of water, what will be the radius of the circular horizon

Options

A. `3` m
B. `(3)/(sqrt(7))` m
C. `sqrt(7)` m
D. `3sqrt(7)` m

Answer

A

Explanation

Refractive index of water, `mu=4//3`

`sinC=(1)/(mu)=(3)/(4)`
`tanC=(3)/(sqrt(7))` ...(i)
From figure
`tanC=(AD)/(OD)=(r)/(sqrt(7))` ...(ii)
From equations (i) and (ii), we get
r= `3` m