A 5.0 diopter lens produces a virtual image which is 4 times the object placed perpendicularly on the principal axis of the lens. Determine the distance of the object from the lens.

Step-by-step solution

Power of the lens, P = 5.0 D Focal length, f = 100 P = 100 5 = 20 cm Since the lens forms a virtual and magnified image, the magnification is m = +4 . Using the relation m = v u , we get v = 4u . Applying the lens formula: 1 v - 1 u = 1 f 1 4u - 1 u = 1 20 1 - 4 4u = 1 20 -3 4u = 1 20 4u = -60 u = -15 cm The distance of the object from the lens is 15 cm .