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

1. no refraction
2. only dispersion
3. only deviation
4. both deviation and dispersion

When a ray of white light falls on a prism, which of the following statements are correct ?

1. The dispersion of white light occurs at the first surface of the prism.
2. The deviation of light rays occurs at both the surfaces of the prism.
3. The prism does not produce colours, but it only splits the various colours present in the white light.
4. All of the above.

Out of red, blue and violet, which colour has the greatest speed in vacuum ?

1. red
2. blue
3. violet
4. all have the same speed

A beam consisting of red, blue and yellow colours is incident normally on the face AB of an isosceles right-angled prism ABC as shown in the figure given below. Critical angle of glass-air interface for yellow colour is 45°.

Out of the four emergent rays P, Q, R and S, which one is for the yellow colour :

1. P
2. Q
3. R
4. S