power 4dA convex lens of power 4D is kept in contact with a concave lens of power 3D, the effective power of combination will be . View Solution; The power of a concave lens is 10 D and that of aA convex lens of power 4D is kept in contact with a concave lens of power 3D, the effective power of combination will be . View Solution; The power of a concave lens is 10 D and that of a