Question

define a main focus of convex lens

Answer 1

Convex lenses are thicker at the middle. ... When parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus. The distance between the principal focus and the centre of the lens is called the focal length.

Answer 2

Focus of convex mirror is ➡a point on principal axis from which light rays incident parallel to principal axis appear to come after reflection from mirror
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