Question

A convex lens of focal length 20cm is mounted on an upright of an optical bench. The image of a

distant object is formed on a screen. A concave lens of focal length 25cm is placed in contact

with the given lens. The screen is moved suitably to focus the image of same distant object.

(a)What is the distance of screen from the convex lens, where image of distant object is

obtained?

(b)How does the combination of lenses behave?

©Where will the image of distant object be formed?

(d)Will the image formed by combination be real or virtual? ​

Answer 1

Real images are produced when the object is located a distance greater than one focal length from the mirror. A virtual image is formed if the object is located less than one focal length from the concave mirror.