Lenses are used in cameras, telescopes, binoculars, microscopes and corrective glasses. A lens can be convex or concave .

To clarify all your doubts about the concave lens and convex lens, students can read this article. Here, the difference between a concave lens and a convex lens has been discussed in detail.

In a ray diagram, a convex lens is drawn as a vertical line with outward facing arrows to indicate the shape of the lens. The distance from the lens to the principal focus is called the focal length .