Two lenses of power `+ 10 D and - 5 D` are placed in contact,  (i) Calculate the focal length
Channel: Doubtnut
Date: 02/08/2020

Two lenses of power `+ 10 D and - 5 D` are placed in contact,  (i) Calculate the focal length of the combination  (ii) where should an object be held from the combination so as to obtain a virtual image of magnification `2` ?