Question

It is desired to photograph the image of an object placed at a distance of $3$ m from a plane mirror. The camera, which is at a distance of $4.5$ m from the mirror should be focused for a distance of :

• A. $3m$
• B. $4.5m$
• C. $6m$
• D. $7.5m$

Answer 1

The correct option is D $7.5m$

The distance between the object and the mirror is $3m$, i.e., $d_1=3m$,

Hence image distance also equals $d_1=3m$

Also, the distance between the mirror and the camera is $4.5m$, i.e., $d_2=4.5m$ .

Hence the focus of the camera,
$f=d_1+d_2=3+4.5=7.5m$