Diameter or aperture of a plano-convex lens is 6 c m and its thickness at the centre is 3 mm. The image of an object formed is real and twice the size of the object. If the speed of light in the material of the lens is 2 × 10 8 m s - 1 . The distance where the object is placed from the plano-convex lens is … … … × 15 c m .

Step-by-step solution

R - y 2 + r 2 = R 2 R = r 2 2 y = 6 2 2 2 × 0 .3 = 15   cm 1 f = μ - 1 R μ = C V = 3 .0 × 10 8 2 .0 × 10 8 = 1 .5 ∴ f = 30   cm converging Now f = 30   cm 1 f = 1 v - 1 u 1 30 = 1 v - 1 u m = v u = - 2 v = - 2 u 1 30 = - 1 2 u - 1 u 1 30 = - 3 2 u u = - 45   cm