Convex lens
A convex lens is thicker at the center than at the edges.
Through a convex lens when a beam of light penetrates, it has converge or become closer
together. It bends parallel light rays towards one another and if they are parallel to the
principal axis of the lens, they converges to a common point(focus, F) behind the lens.B
eams of light from a distant object will converge to a single point or centre called the
focus. Next, light is refracted again when it enters a lens and leaves it. The degree of
curvature of the lens will determine the amount of refraction. A very curved lens will
refract light more than a lens whose surface is slightly curved. The image formed by a
converging lens depends on the position of the object relative to the lens's focal length
(distance between the focus and the optical center) and its centre of curvature.
Concave lens
Concave lenses, lenses that are thinner at the center than
at the edges, bend light rays so that they diverge or bends parallel rays of light passing
through it away from each other. Thus, they produce only virtual images. The image is
formed on the same side of the lens as the object; it is upright and is always diminished,
or smaller than the real object. The size of the image is controlled by the distance of
the object from the lens. The closer the object is to the lens, the larger the image.
