Which statement best describes reflection?

• A. When light bends as it enters a new medium.
• B. When light heats a surface.
• C. When light bounces off a surface.
• D. When light passes through a material.

Answer: (C)

Reflection is the change in direction of light when it hits a boundary and bounces back into the original region. It follows the idea that the angle of incidence equals the angle of reflection, measured relative to the normal to the surface. This sets it apart from refraction, which is light bending as it enters a new medium due to a change in speed, and from absorption or transmission, which involve the light being taken up as heat or simply passing through. A smooth surface like a mirror produces a clear reflection because the light rays reflect in a uniform direction, while a rough surface scatters light in many directions, giving diffuse reflection. The statement that best describes reflection is that light bounces off a surface.