An object is placed 20 cm in front of a plane mirror. The mirror is moved 2 cm towards the object. The distance between the positions of the original and final images seen in the mirror is:

A) 2 cm

B) 4 cm

C) 10 cm

D) 22 cm

Initially, object and mirror distance= 20 cm

Image and mirror distance = 20 cm

Now, mirror is moved 2 cm towards the object,

New distance between object and mirror = 20 cm - 2 cm = 18 cm

New distance between mirror and image = 20 cm - 2 cm = 18 cm,

It is 2 cm less than the distance in initial case.

The total distance between the positions of the original and final images is 2 cm + 2 cm = 4 cm since, the mirror has also moved 2 cm away from the position of original image.