Aluminous object and a screen are placed on an optical bench and a converging
Channel: Doubtnut
Date: 2021-11-10

Aluminous object and a screen are placed on an optical bench and a converging lens is placed between them to throw a sharp image of the object on the screen, the linear magnification of the image is found to be 2.5. The lens is now moved 30 cm nearer the screen and a sharp image is again formed. Calculate the focal length of the lens.