Mission RM1 Law of Reflection
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The diagram depicts light reflecting off a planar surface. The incident ray, reflected ray, normal and surface are labeled with a letter. The incident ray is labeled with a letter ____, the reflected ray is labeled with a letter ____, and the normal with a letter _____.

The diagram shows a mirror surface (denoted by the horizontal line with the yellow backing), two rays of light that have arrowheads to denote the direction of travel, and a normal line. It is common convention to represent light rays by straight lines that have arrowheads at one end.

An incident ray is a ray of light which is approaching a mirror surface.
Definition of Reflected Ray:
A reflected ray is a ray of light which is leaving from (or has reflected off of) a mirror surface.
Definition of Normal Line:
A normal line is a line drawn perpendicular to a mirror surface at the location where a ray of light strikes the surface.