Complete the following sentence:

All the ______ are measured from the Pole of a spherical mirror.

What is the nature of a mirror having a focal length of, +10 cm ?

What kind of mirror can have a focal length of, - 20 cm ?

What sign (+ve or -ve) has been given to the following on the basis of Cartesian Sign Convention?

(a) Height of a real image.

(b) Height of a virtual image.

Describe the New Cartesian Sign Convention used in optics. Draw a labelled diagram to illustrate this is convention.