Question

A ray of light passes through $4$ transparent media with refractive indicies $n_1,n_2,n_3,n_4$ as shown in the figure. The surface of all the medias are parallel. If the emergent ray from the surface $n_3$ to $n_4$ is parallel to the incident ray $AB$, we must have

• A. $n_1=n_2$
• B. $n_2=n_3$
• C. $n_1=n_4$
• D. $n_3=n_1$

Answer 1

Answer: (C)

$n_1=n_4$

The incident ray will be parallel to the emergent ray, if the refractive indices of both the media is same and both the surfaces are parallel to each other. This phenomenon is known as lateral shift

Hence, $n_1=n_4$