Question

An object is placed Infront of a plane mirror 12 cm away from it. The object is kept fixed while the plane mirror is shifted towards the object by a distance of 4 cm. The length of shift in the position of image is equal to ___________ cm.

Answer 1

When an object is placed in front of a plane mirror, the image formed is at the same distance behind the mirror as the object is in front of it. Therefore, the distance between the object and the image is twice the distance between the object and the mirror.
Initially, the object is placed 12 cm away from the mirror. Therefore, the distance between the object and the image is 2 x 12 = 24 cm.
When the mirror is shifted towards the object by 4 cm, the distance between the object and the mirror becomes 12 - 4 = 8 cm. Therefore, the
distance between the object and the image becomes 2 x 8 = 16 cm.
The shift in the position of the image is the difference between the initial and final distances between the object and the image. Therefore, the shift in the position of the image is:
24 - 16 = 8 cm
So the length of the shift in the position of the image is 8 cm.
Answer. 8 cm