A beam strikes an irregular mirror and is reflected as shown below. The angle formed by the incoming beam and the reflected beam is 10 degrees. What is the angle of the mirror's surface (measured against vertical) at the location where the beam strikes the mirror?

A. The mirror's surface is angled 5 degrees upward where the laser strikes it.

B. The mirror's surface is angled 5 degrees downward where the laser strikes it.

C. The mirror's surface is angled 10 degrees upward where the laser strikes it.

D. The mirror's surface is angled 10 degrees downward where the laser strikes it.

The law of reflection states that the angles of incidence and reflection on a surface are the same, the two rays and the normal are in the same part of the surface.

In this exercise indicate that the angle between the incident and reflected ray is 10, therefore the angle with respect to the normal that is a vertical line at the point of contact of the ray must be 5

Consequently the correct answer is B