Question

A pin which is 2 cm long is placed at a distance of 16 cm from a convex lens. Assuming it to be perpendicular to the principal axis, find the position, size and the nature of the image if the focal length of the lens is 12 cm.

Answer 1

Here distance of object $u=-16cm$

Focal length of lens is $f=12$

So $\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$

So $\frac{1}{12}=\frac{1}{v}-\frac{1}{-16}$

$v=48cm$

Image is real

Magnification for lens is $m=\frac{v}{u}=\frac{48}{-16}=-4$

Inverted image and magnified.

Size of image is $h=4\times h_i=4\times 2=8cm$