Question

An object of height 10 cm is kept in front of a convex lens at a distance of 10 cm form its optical centre. Find the position, nature and size of the image if the lens has a focal length of 2 cm.

Answer 1

Given:u=−10cm f=20cm (convex lens)

To find: v and image's nature.

Solution: From lens formula

v

1

−

u

1

=

f

1

v

1

+

10

1

=

20

1

v

1

=

20

−1

v=−20cm

And magnification =

u

v

=2

Hence image formed is virtual, erect and magnified two times