Question

Where should an object be placed from a converging lens of focal length 20cm,
so as to obtain a real magnified image.​

Answer 1

Explanation:

The magnification of the image in a converging lens is 2.

⇒−vu=2⇒v=−2u.

The lens formula for a converging lens is 1v−1u=1f.

⇒−12u−1u=120⇒−32u=120

⇒u=−32×20=−30 cm.

⇒ The object should be placed at a distance of 30 cm from the mirror.