Question

A beam of white light is incident on a triangular glass prism with an index of refraction of about 1.5 for visible light, producing a spectrum. Initially, the prism is in a glass aquarium filled with air, as shown above. If the aquarium is filled with water with an index of refraction of 1.3, which of the following is true?

(A) No spectrum is produced.

(B) A spectrum is produced, but the deviation of the beam is opposite to that in air.

(C) The positions of red and violet are reversed in the spectrum.

(D) The spectrum produced has greater separation between red and violet than that produced in air.

(E) The spectrum produced has less separation between red and violet than that produced in air.

Answer 1

The correct option is: (E) The spectrum produced has less separation between red and violet than that produced in air.

Explanation:

The larger the difference between n’ the more the rays bend. When the water is added, the difference between n’ is less so the amount of bending is less.