Question

if an object of 7 centimetre height is placed at a distance of 12 cm from the convex lens of focal length 8 cm find the position nature and height of the image formed by it

Answer 1

By applying lens formula 1/v-1/u=1/f
u is given -12cm ,f is given 8cm
So, v=24cm
m=h(height of image)/h'(height of object)
Also, m=v/u
Therefore, h/h'=v/u
By applying this, height of image is(h')=-14
And m=h/h'
So, m= -2
m is become negative it means the image is real and inverted

Answer 2

Answer:

Given: U= -12cm, f=+8 cm

Putting these values in the lens formula.

$\frac{1}{v}\:-\: \frac{1}{u}\:=\: \frac{1}{f} \:\: we\:get,\:\frac{1}{v}\:-\: \frac{1}{-12}\:=\: \frac{1}{f}\\\\\frac{1}{v}\:=\: \frac{1}{8}\:-\: \frac{1}{12}\:\:\:thus,\:\frac{1}{v}\:=\:\frac{1}{24}\\V\:=\:+24\:cm\\\\Magnification,\:m\:=\:\frac{v}{u}\:=\:\frac{h1}{h2}\\\\\\m\:=\:\frac{24}{-12}\:=\:\frac{h2}{7},\\\\Thus,\:h2\:=\:-14cm$

Hope it helps you :)