# what is lens

### Asked by shivendralodhi194194 | 26th Jan, 2021, 01:45: PM

Expert Answer:

### A transparent material bound by two surfaces, of which one or both surfaces are spherical, forms a lens.
This means that a lens is bound by at least one spherical surface. If there is only one spherical surface ,
then other surface would be plane.
A lens may have two spherical surfaces, bulging outwards. Such a lens is called a double convexlens.
It is simply called a convex lens. It is thicker at the middle as compared to the edges.Convex lens converges
light rays . Hence convex lenses are called converging lenses.
Similarly, a double concave lens is bounded by two spherical surfaces,curved inwards. It is thicker at the edges
than at the middle. Such lenses diverge light rays . Such lenses are called diverging lenses. A double concave lens
is simply called a concave lens.
A lens, either a convex lens or a concave lens,has two spherical surfaces. Each of these surfaces forms a part of a sphere.

### Answered by Thiyagarajan K | 26th Jan, 2021, 02:27: PM

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