A convex lens of focal length ' f ' m forms a real, inverted image twice in size of the object. The object distance from the lens in metre is

Step-by-step solution

aligned & Focal length = f & ~m = v u = h ^ h =-2 ...(given) & v =-2 u aligned From lens formula, aligned & 1 v - 1 u = 1 f & 1 -2 u - 1 u = 1 f & u+2 u 2 u^2 = 1 f & 3 u 2 u^2 = 1 f & 1.5 u = 1 f & u=1.5 f aligned