An object of height 4.2S mm is placed at a distance of 10 cm from a convex lens of power +S D. Find (i) foe length of the lens, and (ii) size of the image.

Fill in the following blanks with suitable words :

(a) The reciprocal of the focal length in ____ gives you the power of the lens, which is measured in........

(b) For _____ lenses, the power is positive while for diverging lenses, the power is negative

An object of height 4 cm is placed at a distance of 1S cm in front of a concave lens of power, -10 dioptres. Find the size of the image.

A convex lens of power S D and a concave lens of power 7.5 D are placed in contact with each other. What is the:

(a) power of this combination of lenses?

(b) focal length of this combination of lenses ?

A convex lens of focal length 2S cm and a concave lens of focal length 10 cm are placed in close contact with one another.

(a) What is the power of this combination?

(b) What is the focal length of this combination?

(c) Is this combination converging or diverging ?