Question

why do in automobiles, the rear view mirrors have warning written as 'object seen in the mirror may be closer than they appear'?

Answer 1

The rear view mirrors in the automobiles are concave mirror, because concave mirror produces an erect and enlarged image enabling to have a larger field of view. Concave mirror produces an virtual image, of magnified size and at more distance that of object, this means that the object seen in the mirror is far than it actually is. Hence it is mentioned as a warning on the mirror 'object seen in the mirror may be closer than they appear'.
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Hope this helped ^_^

Answer 2

object in the mirror are closer than the appear