A ray of light is incident at an angle of 20degrees to the normal on one face of an equilateral prism made in glass of refractive index 1.523. Find the total deviation produced.
n(relative)=n(glass)/n(air)=n(glass)=
=n=1.523
For equilateral prism α=60°
n(relative)=sin{½• (α+θ)}/sin(½•α)
sin{½• (α+θ)}= n• sin(½•α)=1.583•sin30°=0.7915
½• (α+θ)}=sin⁻¹0.7915=52.3°
α+θ= 60°+θ=2•52.3°=104.6°
Minimum deviation angle is
θ=104.6°-60° =44.6°