Question
An object of height 6 cm is placed perpendicular to the principal axis of a concave lens of focal length 5 cm. Use lens formula to determine the position, size and nature of the image if the distance of the object from the lens is 10 cm.
Solution
Given,
Height of object, h1 = 6 cm,
Focal length of lens, f = -5 cm, and
Object distance, u = -10 cm
Now, using the lens formula, 
Thus, the image of size 2 cm will be formed in front of the lens at a distance of 3.33 cm from the lens. The nature of the image is virtual and erect.
