Question

A sharp image of a distant object is obtained on a screen by using a convex lens. In order to determine the focal length of the lens. you need to measure the distance between the

• A. lens and the object
• B. lens and the screen
• C. object and the screen
• D. lens and the screen and also object and the screen

Answer 1

Answer: (B)

lens and the screen

When the object is at infinity, its image is formed at the focus of the lens. For determination of the focal length of the lens, the distance between the lens and the screen should be measured because all the rays converges at a common point on the screen.