Mirror

:This article is about the reflective surfaces. For other senses of this word, see mirror (disambiguation).

Effect

In a plane mirror, a parallel beam of light changes its direction as a whole, whilst still remaining parallel; the images formed by a plane mirror are virtual images, of the same size as the original object (see mirror image). There are also parabolic concave mirrors, where a parallel beam of light becomes a convergent beam, whose rays intersect in the focus of the mirror. Finally, there are convex mirrors, where a parallel beam becomes divergent, with the apparent intersection occurring behind the mirror. Note that spherical concave and convex mirrors do not have a single focal point, as often described in high school physics text books (see spherical aberration in lens (optics) and aberration in optical systems).

Related Topics:
Parallel - Light - Mirror image - Parabolic - Concave - Convergent - Focus - Convex - Spherical aberration in ''lens (optics)'' - Aberration in optical systems

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A beam of light reflects off a mirror at an angle of reflection that is equal to its angle of incidence. That is, if the beam of light is shining on a mirror's surface at a 30° angle from vertical, then it reflects from the point of incidence at a 30° angle from vertical in the opposite direction.

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Contrary to popular belief, mirrors do not actually reverse left-to-right; they actually reverse front-to-back. Light rays reflecting off a mirror have their front-to-back direction reversed, while the left-to-right and top-to-bottom components of their direction remain unchanged. The confusion comes from the perception that if a person were standing behind the mirror facing us, as our reflection seems to, then they would be reversed left-to-right relative to ourselves. However, this left-to-right reversal is not performed by the mirror, but rather by this imaginary person turning around left-to-right to face us from behind the mirror.

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