Question
The image of an object formed by a mirror is real, inverted and is of magnification 21. If the image is at a distance of 40 cm from the mirror, where is the object placed? Where would the image be if the object is moved 20 cm towards the mirror? State reason and also draw ray diagram for the new position of the object to justify your answer.
Solution
The object will be placed at centre of curvature.
If the object is moved 20 cm towards the mirror, then image will be formed at infinity. Here, focal length of the mirror is 20 cm. And the new position of the object would be at the focus of the mirror.
The ray diagram for the formation of the image is as shown below:
