reflection: Quick Facts

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Two diagrams compare light reflection: the top shows blue incident and reflected rays bouncing off a smooth surface, with equal angles from the normal; the bottom shows rays scattering from a rough surface, with normals and angles marked at various points.

$Figure 7: The refraction and reflection of light. (Left) When light strikes the boundary between glass and air at less than the critical angle (θc), it is refracted and partially reflected; (centre) when it meets the boundary at the critical angle, it is refracted parallel to the boundary; (right) when it meets the boundary at more than the critical angle, it is reflected totally.$