Answer:
A lens bends a light beam at an aimed angle and converges or diffuses bundles of rays by taking advantage of refraction taking place when the light travels. For that purpose, the side geometry of a lens has a spherical figure, which may be roughly divided into two types.
Concave lens and
Convex lens.
In short if a light ray passes through a lens, then it will bend.
When it passes through concave lens: the ray of light passing through the concave lens will bend further away from principal axis after refraction.
When it passes through convex lens: the ray of light after passing through the convex lens will towards the principal axis.