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.

The focal length of a lens is +150 mm. What kind of lens is it and what is its power ?

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 4.2S 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.

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 ?