# Question 6

A light ray is incident on a glass prism. The angle of incidence is 38°, as shown below.
The refractive index of glass is 1,5 and that of air is 1.

6.1 Define the term angle of refraction. (2)

6.2 Calculate the angle of refraction inside the glass prism. (3)

6.3 Redraw the glass prism in the ANSWER BOOK. Complete the path of the  light ray inside the prism and label the angle of refraction. (2)

A second prism, Q, of unknown material, is now placed next to the glass prism, as  shown in the diagram below.

The light ray travels from the glass prism and enters prism Q at an angle of incidence  of 36°. The angle of refraction inside prism Q is 41°.

6.4 Calculate the refractive index of prism Q. (2)

6.5 How does the speed of light in the glass prism compare to the speed of light  in prism Q? Write only GREATER THAN, SMALLER THAN or REMAINS THE SAME. (1)

6.6 Explain the answer to QUESTION 6.5 by referring to the refractive indices of  the materials. (2)

The critical angle for the glass prism Q boundary is 63,3°. The angle of incidence when   the light ray travels from the glass prism to prism Q is increased to 65°.

6.7 Define the term critical angle. (2)