The focal lengths of four convex lenses P, Q, R and S are 20 cm, 15 cm, 5 cm and 10 cm, respectively. lens having greatest power is:

Two lenses A and B have power of (i) + 2 D and (ii) - 4 D respectively. What is the nature and f length of each lens ?

An object is placed at a distance of 100 cm ,from each of the above lenses A and B. Calculate (i) image distance, and (ii) magnification, in each of the two cases.

A converging lens has a focal length of 50 cm. The power of this lens is:

A diverging lens has a focal length of 0.10 m. The power of this lens will be: