Question

A light ray strikes a plane mirror at an angle of 70° to the normal. What is the angle that the reflected ray makes with the surface of the mirror?

Group of answer choices

120°

20°

70°

35°

Answer 1

To find the angle that the reflected ray makes with the surface of the mirror, we can use the laws of reflection. According to these laws:

1. The angle of incidence is equal to the angle of reflection.
2. Both angles are measured with respect to the normal (the line perpendicular to the mirror's surface).

Given that the light ray strikes the mirror at an angle of 70° to the normal, the angle of incidence is 70°.

By the law of reflection:
- The angle of reflection is also 70° to the normal.

Now, to find the angle with respect to the surface of the mirror, we need to calculate it. The angle that the reflected ray makes with the surface is complementary to the angle of reflection because the angles must add up to 90°.

Therefore, the angle that the reflected ray makes with the surface is:
\[ 90° - 70° = 20°. \]

So, the angle that the reflected ray makes with the surface of the mirror is **20°**.