A total reflecting prism is:

1. right-angled prism
2. equilateral prism
3. right-angled isosceles prism
4. all of the above

An equilateral prism can be used to deviate a ray of light through:

1. 30°
2. 60°
3. 75°
4. 90°

In the figure given below, the ray PQ emerging from the object P is refracted along QS. The angle PQN is known as:

1. angle of deviation
2. angle of refraction
3. critical angle
4. none of the above

The diagram below shows a light source P embedded in a rectangular glass block ABCD of critical angle 42°. The ray PQ would:

1. pass undeviated
2. suffer refraction
3. suffer reflection
4. suffer total internal reflection