power 4dTo find the effective power of a combination of a convex lens and a concave lens, we can follow these steps: 1. Identify the Powers of the Lenses : - The power of the convex lens (P1) is given6. A convex lens of power +6 D is placed in contact with a concave lens of power –4D. What will be the nature and focal length of this combination ? (a) convex, 100 cm (b) convex, 50 cm