Question

differentiate between concave and convex lens..

Answer 1

Concave lens are those lens which diverge the light rays when the light rays are pass in through it.In concave lens the lights rays seems to meet at behind the lens at the focus point

Convex lens are those lens which converge the light rays at the focus point...
In convex lens the light rays actually meet at the focus point...

Answer 2

$\textbf{Answer is in Attachment !}$