The distance between the image and the object in a plane mirror is 40cm if the distance of the object is reduced by 9.2cm, what is the mirror?

Explanation:

The question is:

To answer this question, you must learn that, for plane mirrors, the distance of the object from the mirror is equal to the distance of the image formed behind the mirror.

For instance if you stand 1 meter away from a mirror (a plane one) the position of the image of you will be 1 meter behind the mirror.

Here, the initial distance between the image and the object is 40 cm. Then, the distance between the image and the miror is 20 cm, such as it is the distance between the object and the mirror.

That the distance of the object is reduced by 9.2 cm, must be understood as that the object was placed 9.2 cm closer to the mirror.

Then, the new distance of the object from the mirror is 20 cm - 9.2 cm = 10.8 cm. ← answer