Derive the lens formula, `(1)/(2)=(1)/(v)-(1)/(u)` for a concave lens, using the necessary ray
Channel: Doubtnut
Date: 03/01/2020

Derive the lens formula, `(1)/(2)=(1)/(v)-(1)/(u)` for a concave lens, using the necessary ray diagram. Two lenses of powers 10 D and -5 D are placed in contact. (i) Calculate the power of the new lens. (ii) Where should an object be held from the lens, so as to obtain a virtual image of magnification 2?