Two monochromatic rays of light are incident normally on the face AB of an isosceles right-angled prism ABC. The refractive indices of the glass prism for the two rays '1' and '2' are respectively 1.35 and 1.45. Trace the path of these rays after entering through the prism.

Critical angle is given by: θc=sin⁻¹(1/μ)
For ray 1, i=45°=sin⁻¹(1/1.414)
θc1=sin⁻¹(1/1.35)>sin⁻¹(1/1.414)
Hence, θc1>i
Ray will not undergo total internal reflection.
Applying Snell's law, 1.35sin(45°)=1sin(θr)
sin(θr)=0.9545
θr≈72°
For ray 2, i=45°=sin⁻¹(1/1.414)
θc2=sin⁻¹(1/1.45)
θc2=sin⁻¹(1/1.45)<sin⁻¹(1/1.414)
Hence, θc1<i
Ray will undergo total internal reflection.