A 60° prism has a refractive index of 1.5 Calculate the angle of incidence for minimum deviation, the angle of emergence of light at maximum deviation and angle of maximum deviation.
The formula relating refractive index, Angle of prism and angle of minimu deviation is 
, where μ is the refractive index, A is angle of prism and Dm is minimum angle of deviation by substituting A = 60º, μ=1.5 and solving for Dm we get, Dm = 37.2°.
Maximum angle of deviation occurs when incident angle i is 90°.
As shown in figure, angle of deviation δ is given by, δ = i + e - A …(1)
also we have, r + r’ = A …(2)
for maximum angle of deviation,
from eqn.(2), r’ = A-r = 60 - 41.8 = 18.2º
to get angle of emergence e, we have
from eqn.(1), we get maximum angle of deviation, δ = 90+27.94-60 = 57.94 º