" 4) Define principal focus of a convex lens."

Principal focus of convex lens:

Principal focus of convex lens:

a) Explain with the help of a diagram, why the concave lens is also called a diverging lens. b) Define the principle focus of a convex lens.

Principal focus of concave lens:

Principal focus of concave lens:

Draw a ray diagram in each of the following cases to show the formation of image, when the object is placed : between optical centre and principal focus of a convex lens.

Define principal focus of a mirror.

Define the principal focus of a lens.