The angle at which a ray of light bounces off a surface is called the angle of reflection. It is equal to the angle of incidence, which is the angle between the incoming ray and the normal (a line perpendicular to the surface at the point of incidence).

Here's a breakdown:

* Angle of Incidence (i): The angle between the incoming ray of light and the normal.

* Angle of Reflection (r): The angle between the reflected ray of light and the normal.

Law of Reflection: The angle of incidence is equal to the angle of reflection (i = r).

Example: If a light ray hits a mirror at an angle of 30 degrees to the normal, it will bounce off the mirror at an angle of 30 degrees to the normal.

Note: This principle applies to all types of surfaces, not just mirrors. However, the smoothness of the surface affects how much the light is scattered.