A screen is placed 90 cm from an object. The image an object on the screen is formed by a convex lens two different locations separated by 20 cm. Determine the focal length of the lens is A screen is placed 90 cm from an object. The image an object on the screen is formed by a convex lens two different locations separated by 20 cm. Determine the focal length of the lens is November 19, 2020 Category: Chapter 9 - Ray Optics and Optical Instruments , NCERT Exemplar Class 12 , Physics , Facebook Messenger WhatsApp Share this:TwitterFacebook Related