Show with the help of a diagram how a total reflecting prism can be used to turn a ray of light through 90°. Name one instrument in which such a prism is used.

A ray of light XY passes through a right-angled isosceles prism as shown in the adjacent diagram.

(a) What is the angle through which the incident ray deviates and emerges out of the prism?

(b) Name the instrument where this action of prism is put into use.

(c) Which prism surface will behave as a mirror?

In the figure given below, a ray of light PQ is incident normally on the face AB of an equilateral glass prism. Complete the ray diagram showing its emergence into air after passing through the prism. Take critical angle for glass = 42°.

(a) Write the angles of incidence at the faces AB and AC of the prism.

(b) Name the phenomenon which the ray of light suffers at the face AB, AC and BC of the prism.

In the figure, a ray of light PQ is incident normally on the hypotenuse of an isosceles right angled prism ABC.

(a) Complete the path of the ray PQ till it emerges from the prism. Mark in the diagram the angle wherever necessary.

(b) What is the angle of deviation of the ray PQ?

(c) Name a device in which this action is used.