When a glass prism of refracting angle `60^(@)` is immersed in a liquid its angle of minimum deviation is `30^(@)`. The critical angle of glass with respect to the liquid medium is

Options

A. `42^(@)`
B. `45^(@)`
C. `50^(@)`
D. `52^(@)`

Answer

B

Explanation

`n = (sin ( (A + delta_(m))/(2) ) )/(sin (A)/(2) ) = (sin 45^(@))/(sin 30^(@)) = sqrt(2)`
Critical angle ,
`i_(c ) = sin^(-1) ((1)/(n)) =sin^(-1) ((1)/(sqrt(2))) = 45^(@)`.