Question

Define the principal focus of a concave lens.

Answer 1

Answer:

The principal focus of a concave lens is a point on principal axis from which light rays, originally parallel to the axis appear diverge after passing through the concave lens.

Answer 2

Answer:

The principal focus of a convex lens is defined as the point on which the principal axis of the light is parallel to the principal axis that converges after the refraction from the lens. The principal focus of concave lens is when the light rays get diverged and appear to form a single point.