In the figure two triangular prism are shown each of refractive index `sqrt3` .
(a) Find the angle of incidence on the face `AB` for minimum deviation from the prism `ABC` ?
(b) Find the angle through which the prism `DCE` should be rotated about the edge passing through point `C` so that there should be minimum deviation from the system ?

Answer

(a)`i=60^(@);`(b)`60^(@)`

Explanation

(a) At minimum deviation, `r_(1)=r_(2)=30^(@)`
`therefore` From Snell's law `mu=(sin i_(1))/(sin r_(1))` or `sqrt3=(sin i_(1))/(sin 30^(@))`
`therefore sin i_(1)=(sqrt3)/(2)` or `i_(1)=60^(@)`
(b) In the position shown below net deviation suffered by the ray of light should be minimum. Therefore, the second prism should be ratated by `60^(@)` (anticlockwise).