Question

what is lens?? explain.
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Answer 1

Lens is a transparent medium bounded by two surface of which one or both surfaces are spherical

$\underline \bold{ \large{Types \: of \: lens \: : \: }}$

Convex lens

A lens which is thicker at the centre and thinner ar its ends us called convex lens

Concave lens

A lens which is thinner at the centre and thicker at its ends us called a concave lens