A parallel beam of light after refraction appears to diverge from the principal focus. What kind of lens is it?

A parallel beam of light after refraction through a lens, converges toward its principal focus. What kind of lens is it?

Define the principal focus of a lens.

Principal focus of concave lens:

Principal focus of concave lens:

Principal focus of convex lens:

Principal focus of convex lens:

A symmetrical bioconcave lens having radius of curvature R is made up to two different materials as shown in figure. A parallel beam of light passing through the lens appear to diverge from two different points. Find the distance between them.

Assertion : A parallel beam of light passing through the concave lens , is diverged or spread out Reason : A convex lens is also called as diverging lens.