Question

If the two focal length of a convex lens are equal then is is a symmatrical lens

Answer 1

The focal length will remain constant if a convex lens is cut in half horizontally because the focal length of a lens depends on its two radii of curvature and the material of the lens. As no change in the material or curvature occurs, the focal length of the lens will remain constant. Only the brightness of the image would be reduced as only half of the previous amount of light will be intercepted by the lens.