Question

A 6 cm tall object is placed perpendicular to the principal axis f a convex lens of focal length 15 cm. The distance of the object from the lens is 10 cm. Find the position, size and nature of the image formed.

Answer 1

Lens formula :

1/f = 1/u + 1/v

u = 10

f = 15

1/15 = 1/10 + 1/v

1/15 - 1/10 = - 1/30

The image distance = -30cm

Magnification = 30/10 = 3

Magnification = image height / object height

3 = hi/6

Hi = 3 × 6 = 18cm

The image is virtual since the image distance is negative.