A light ray is incident on a glass sphere at an angle of incidence `60^(@)` as shown. Find the angles r, r', e and the total deviation after two refractions.

Explanation

Applying snell's law `1 sin 60^(@)=sqrt(3) sin r`
`rArr r=30^(@)`
From symmetry `r'=r=30^(@)`
Again applying snell's law at second surface
`1 sin e=sqrt(3) sin r`
`rArr e=60^(@)`
Deviation at first surface `=i-r`
`=60^(@)-30^(@)=30^(@)`
Deviation at second surface `=e-r'`
`=60^(@)-30^(@)=30^(@)`
Therefore total deviation `=60^(@)`