Why inversion occurs laterally? not vertically!

Asked by ravikiranandra | 19th Oct, 2009, 12:59: PM

Expert Answer:

It is possible to show that a plane mirror causes inversion, vertical or lateral. Consider the formation of an image as shown in figure 1. For simplicity. the object is a two-dimensional Cartesian coordinate system. Both object and image lie in planes parallel to the mirror surface. Neither axis is reversed. There is no vertical inversion. There is no lateral inversion.


Both figures 2 and 3 consider an object lying in a plane perpendicular to the mirror surface, not parallel to it. Consequently they merely indicate that object points near to a mirror have images near to a mirror, and that points further from the mirror produce images further from the mirror. This is longitudinal inversion. However, as shown in figure3, if the observer rotates his frame of reference and views parallel to the plane of the mirror his

directions of left and right will lie perpendicular to the mirror surface, and consequently because of this rotation when looking at the object,  he will associate left with being far from the mirror and right being  near to the mirror. From observer A’s view-point both the object notice and its image remain at the left of his field of view, indicating no inversion: but observer B. having rotated his reference frame, will see an image in which left and right seem to be reversed. The effect however is caused not by the mirror, but by B’s rotation.





Answered by  | 10th Nov, 2009, 11:51: AM

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