The angle between a reflected ray and the normal to a surface is called?

• A. Normal line
• B. Focal point
• C. Angle of reflection
• D. Ultraviolet

Answer: (C)

This question is about how angles are defined in reflection. The law of reflection says that the angle between the incoming ray and the normal equals the angle between the reflected ray and the normal. The angle described—between the reflected ray and the normal—is the angle of reflection. The normal line is just the reference line perpendicular to the surface, not the name of the angle. The other terms don’t fit: a focal point is where rays meet after curved surfaces, and ultraviolet is a part of the light spectrum, not an angle. For example, if the incoming ray makes 40 degrees with the normal, the reflected ray also makes 40 degrees with the normal.