Question

A beam of white light traveling in medium A strikes the interface to another transparent medium, medium B. If the speed of white light is less in medium B than in medium A, the beam will
(A) refract toward the normal
(B) refract away from the normal
(C) undergo total internal reflection
(D) have an angle of reflection smaller than the angle of incidence
(E) have an angle of reflection greater than the angle of incidence

Answer 1

Hint
Snell’s law, in optics, the relationship between the path taken by a ray of light in crossing the boundary or surface of separation between two contacting substances and the refractive index of each. The relationship between the angles of incidence and refraction and the indices of refraction of the two media is known as Snell's Law. Snell's law applies to the refraction of light in any situation, regardless of what the two media are.

Complete step by step answer
As the speed of light is lesser in medium B therefore its refractive index will be greater than medium A it means medium B is denser than medium A, we know when light refracts in a denser medium from a rarer medium, it bends towards the normal. So, the beam will refract toward the normal.
Hence the correct option is (A).

Note
When light travels from one medium to another, the speed changes, as does the wavelength. The change in speed that occurs when light passes from one medium to another is responsible for the bending of light, or refraction, that takes place at an interface. If light is travelling from medium 1 into medium 2, and angles are measured from the normal to the interface, the angle of transmission of the light into the second medium is related to the angle of incidence by Snell's law. The critical angle can be found from Snell's law, putting in an angle of 90° for the angle of the refracted ray.