A glass prism of angle `72^(@)` and refractive index `1.66` is immersed in a liquid of `mu = 1.33`. Calculate the angle of minimum deviation.

Answer

`22.38^@`

Explanation

`mu = (sin(A + delta_m))/(sin A//2)`
`"sin"((A + delta_m))/(2) = mu " sin" (A)/(2) = (1.66)/(1.33) "sin" (72^@)/(2)`
`=(1.66)/(1.33) xx 0.5876 = 0.7333`
`:. (A + delta_m)/(2) = sin^-1 0.7333 = 47.19^@`
`:. delta_m = 2 xx 47.19 - A`
=`94.38^@ -m 72^@ = 22.38^@`.