Convex lens is a type of optical lens that has a curved surface on one side and a flat surface on the other. The curved surface bulges outwards and is thicker at the center than at the edges, causing it to converge light rays that pass through it.

The focal length of the lens, which is the distance from the center of the lens to the point where parallel light rays converge, is 20 cm.

The power of the lens, which is a measure of its ability to refract light, is determined by the curvature of the lens surface and its refractive index.

A lens with a greater curvature or a higher refractive index will have a higher power.