An object is placed at a distance of `40 cm` from a concave mirrorr of focal length `15 cm`. If the object is displaced through a distance of `20 cm` towards the mirrorr, the displacement of the image will be

Options

A. `30 cm` towards the mirror
B. `36 cm` towards the mirror
C. `36 cm` away from the mirror
D. `30 cm` away from the mirror

Answer

C

Explanation

`1/(v_(1))+1/(-40)=1/(-15) implies v_(1)=-24 cm`
`1/(v_(2))+1/(-20)=1/(-15) implies v_(2)=-60 cm`
Shift `=60-24=36 cm`, away from mirror.