Question

A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. [Delhi]

Answer 1

Given -

v=(-15)cm

f=(-20)cm

h=5cm

To Find-

the size of the image formed.

Solution-

By using lens formula-

1/v-1/u=1/f

1/u=1/v-1/f

1/u=1/(-15)-1/(-20)

By taking LCM =(300)

1/u=-20+15/300

1/u=-5/300

u=(-60)cm

By using Magnification forumla

m=-v/u=h₁/h₂

=(-15/-60)5

=5/4

m=1.25cm

Hence image will formed Virtual and Diminished

Answer 2

hi friends

here is your answer