Question

A 4 cm tall object is placed on the principal axis of a convex lens. The distance of the object from the optical centre of the lens is 12 cm and its sharp image is formed at a distance of 24 cm from it on a screen on the other side of the lens. If the object is now moved a little away from the lens, in which way(towards the lens or away from the lens) will he have to move the screen to get a sharp image of the object on it again? How will the magnification of the image be affected?

Answer 1

Object distance, u = – 12 cm
Image distance, v = 24 cm

If the object is moved away from lens, the screen will also be moved towards the lens because otherwise the object distance will increase and hence the image distance will decrease.

Since, m=v/u , the magnification will decrease.