Question

Choose the correct alternative and rewrite the following sentence.

A ray of light strikes the glass slab at an angle of 50°. What is the angle of incidence?

Options

• 50°

• 90°

• 60°

• 40°

Answer 1

40°

The ray of light strikes at an angle of 50 with the horizontal. The angle of incidence is with respect to the normal, so the angle of incidence is 90° − 50° = 40°.