find solution this question belongs to Ray optics i have tried no of times but not getting

Actually there is no shadow formed .

Therefore the value of n is 0.

Explanation:

Let a light Ray falls on sphere  at an angle teta after refraction it is making angle alpha with the the line joining centre of the sphere and point of contact of ray . The ray travelling by gracing the medium.sin (teta) =(√3)sin(alpha)

sin(alpha)=1/2 

Therefore teta =60° that means this ray ray falls at the bottom most point .

Hence there is no shadow formed.But intensity of light changes