Question

White light is incident on the triangular face of the prism shown:

Assuming the light emerges out of the other triangular face of the prism, what will be the colour of light visible at the other end? Give your reasons.

Answer 1

Since both the triangular faces of the prism are parallel to each other, the prism will be seen as a glass slab from the point of view of light.
As the light enters the triangular face, it splits into $7$ colours due to the difference in speeds of the different colours of light. At the other face, since it is parallel to the incident face, the light gets recombined as it emerges out of the prism. Therefore, we will only see white light emerging out of the other face of the prism. Also, the emergent ray will be parallel to the incident ray, but displaced laterally.