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The diagram shows a mirror surface (denoted by the black diagonal line with the yellow backing), an incident ray (denoted by the red line with the arrowhead), and five possible reflected rays (denoted by the green lines with the arrowheads). It is common convention to represent light rays by straight lines that have arrowheads at one end to indicate the direction of travel.
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The Law of Reflection:
When a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection. The incident ray and reflected ray are always located within the same plane.
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With the incident ray and the mirror surface drawn, you should be able to determine the angle of incidence. Either eyeball a quick estimate or position a transparent protractor on the screen and measure it. The angle of reflection should be equal to the angle of incidence (see Know the Law section). Only one of the five green rays has an angle of incidence equal to the angle of reflection. You can use the protractor (or a simple estimate) to determine which ray it is.
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