Question

Choose the correct answer:
A ray of light composed of blue light and red light is incident on
a plate of glass as indicated. When the light emerges from the
other side of the plate,
(a) the two colored beams appear at different points and
propagate in different directions
(b) the two colored beams appear at the same point and
propagate in the same direction.
(c) the two colored beams appear at the same point and
propagate in different directions.
d) the two colored beams appear at different points and
propagate in the same direction.
(e) the blue beam will not emerge at all because it suffers
internal reflection.

Answer 1

1. The speeds of ligtht beams with different wavelenghts are different it the glass (see https://en.wikipedia.org/wiki/Dispersion_(optics)). Thus, the two colored beams appear at different points.

2. Again, because of the different speed, the incident angle (and hence the refraction angle) on the surface glass-air is different for different colours. Thus, they propagate in different directions.

Answer. a) the two colored beams appear at different points and propagate in different directions.