Question

The angle of a prism is `60^(@)` When light is incident at an angle of `60^(@)` on the prism, the angle of emerge is `40^(@)`. The angle of incidence `i` for which the light ray will deviate the least is such that
A. `I lt 40^(@)`
B. `40^(@) lt I lt 50^(@)`
C. `50^(@) lt I lt 60^(@)`
D. `I gt 60^(@)`

Answer 1

Correct Answer - B
For min deviation
`i=e`

`r_(1)=r_(2)=(A)/(2)`
`:. r_(1)=r_(2)=30^(@)`
For minimum deviation `i` should lie between 40 to `50^(@)`