Lenses

A lens is any transparent material having two surfaces of which at least one is curved. Lenses refract light in such a way that an image of the object is formed. Lenses of many types are used in optical devices such as cameras, eyeglasses, microscopes, telescopes, and projectors. They also enable millions of people to see clearly and read comfortably.

There are different types of lenses. The lens which causes incident parallel rays to converge to a point is known as covex lens. Another type of lens causes incident parallel rays of light to diverge from a point. This is called concave lens.

The convex lens is thick at the centre but thin at the edges. The concave lens is thin at the centre but thick at the edges.