Question

* A 2.0 cm long pin is placed perpendicular to the principal axis of a convex lens of focal length 12cm the distance of the pin from the lens is 15cm . Find the size of the image.​

Answer 1

Here, u = -15cm, f= 12cm, h1= 2cm, v=?.

h2=?

Using lens formula,

1/f = 1/v - 1/u

=> 1/v = 1/f + 1/u

=> 1/v = 1/12 + 1/(-15)

=> 1/v = 1/60

=> v = 60cm which indicates that the image formed is real and inverted.

Now magnification = v/u = h2/h1

Hence, 60/(-15) =h2/2

=> h2 = 8cm

-ve sign indicates inverted image. Hence, the size of the image is 8cm.