Question

A man standing in front of a plane mirror finds his image at a distance $6$ metres from himself. What is the distance of man from the mirror?

• A. $9m$
• B. $12m$
• C. $6m$
• D. $3m$

Answer 1

Answer: (D)

$3m$

A characteristic of plane mirror images pertains to the relationship between the object's distance to the mirror and the image's distance to the mirror. For plane mirrors, the object distance is equal to the image distance. That is, the image is the same distance behind the mirror as the object is in front of the mirror. If we stand at a distance of $2$ meters from a plane mirror, we must focus at a location $2$ meters behind the mirror in order to view our image.
In this case, the distance between the man and the image is $6$ m. So, the man is located $3$ m from the mirror and the man's image will be located $3$ m behind the mirror.
Hence, the distance between the object and the mirror is $3$ m.