Unformatted text preview: o angle, we know that it reflects straight back. Tracing this ray behind the mirror, we see the image will be at the same height as the object. The image will form at a point where a general ray, when traced back, will cross this perpendicular line. From the diagram, we see that θ 1 = θ 2 from opposite internal angles, θ 2 = θ 3 from the Law of Reflection, θ 3 = θ 4 from crossing parallel lines, and so θ 1 = θ 4 . Since the length L is the same in the two triangles, and both have two equal angles, we know the triangles are congruent, and so the image must be at the same distance from the mirror as the object! Isn't physics wonderful?!?...
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- Fall '11
- Specular reflection, incident ray, simple geometric proof