(b) An object is D cm from a screen. A convex lens forms an image of it on the screen. When moved through a distance x cm, it forms another image. Prove that the ratio of the sizes of the two images produced is D + x D - x 2 [2 + 3] Share with your friends Share 3 Vijay Shankar Yadav answered this Dear Student, In first case let object distance is u and screen distance is vthen u+v=D---1in second case this distances will enterchange sov-u=x---2solve 1 and 2 we getv=(D+x)/2and u=(D-x)/2so ratio of magnification of first case and of second case =vuuv=vu2=D+xD-x2 Regards 1 View Full Answer