A ray of light falls on a transparent sphere with centre at C as shown in figure. The ray emerges from the sphere parallel to line AB. The refractive index of the sphere is

Explanation

Deviation by a sphere is `2(i-r)`
Here, deviation `delta=60^@=2(i-r)`
or `i-r=30^@`
`rArr r=i-30^@=60^@-30^@=30^@`
`:.mu=(sini)/(sinr)=(sin60^(@))/(sin30^(@))=sqrt(3)`