A lens is a piece of transparent material that is usually circular in shape and has two polished surfaces, one or both of which is curved and may be convex or concave.
Curves are almost always spherical, which means that the radius of curvature is constant.
Applications of lenses:
Cameras, telescopes, microscopes, and film projectors all use lenses.
There are also two lenses in our eyes that allow us to see the world around us.
Many different types of lenses are used in optical devices such as cameras, spectacles, microscopes, telescopes, and projectors.
Convex lenses are used in eyeglasses to correct farsightedness, which occurs when the distance between the eye's lens and retina is too short, causing the focal point to be behind the retina.
Concave lenses are used to magnify objects in telescopes and binoculars.