Question

White light is incident on the surface of glass and air as shown. Green light just grazes the surface, then the emergent ray in the air contains

Answer 1

Since green light grazes the surface after refraction the incident angle must be critical angle for green light.

As wavelength increases from violet to Red, the refractive index $\mu$ decreases from Violet, to Red.

and Since ${\theta }_c={\sin }^{-1}\frac{1}{\mu }$ we have critical angle increases from Violet to Red.

Critical angle for yellow orange and red and greater than ${\theta }_g$

Therefore they will emerge out in air, the other colours will be totally internally reflected.