A convex lens of focal length 25 cm is placed coaxially in contact with a concave lens of focal length 20 cm. Determine the power of the combination. Will the system be converging or diverging in nature ?
Power of convex lens = 1/0.25 = 4D
Power of concave lens = - 1/0.20 = - 5D
Power.of the combination, P = P1 + P2 = - ID