Define the principal focus of a concave lens.

Define principal axis, principal focus and focal length of a convex lens.

Explain with the help of a diagram, why the concave lens is also called a diverging lens.

Draw a ray diagram to show the formation of a real magnified image by a convex lens. (In your sketch the position of object and image with respect to the principal focus of lens should be shown clearly).

Describe with the help of a ray-diagram, the formation of image of a finite object placed in front of a convex lens between f and 2f Give two characteristics of the image so formed.