Question

When a white light ray falls on a prism, the ray at its first surface suffers.

(a) no refraction

(b) only dispersion

(c) only deviation

(d) both deviation and dispersion

Answer 1

Both deviation and dispersion.

Hint: When a white light ray falls on the first surface of a prism, light rays of different colours due to their different speeds in glass get refracted (or deviated) through different angles. Thus, the dispersion of white light into its constituent colours takes place at the first surface of prism.