In specular reflection, the relationship between the angle of incidence and the angle of reflection is:

• A. It Equals the Incidence Angle
• B. Not Dependent on Incidence Angle
• C. Twice the Incidence Angle
• D. Half the Incidence Angle

Answer: (A)

The main idea being tested is the law of reflection for a smooth surface: the angle of incidence equals the angle of reflection when measured from the normal to the surface. The incident ray, the reflected ray, and the normal all lie in the same plane, and the surface normal is the reference line for measuring those angles. So if a ray hits at 30 degrees to the normal, it will leave at 30 degrees on the other side of the normal. This symmetry is what makes specular reflection look like a perfect mirror. This relationship holds for all incidence angles on an ideal smooth surface, though on rough surfaces the reflected light scatters in many directions, not adhering to a single equal angle.