Question

An object of size 7.0cm is placed at 237cm in front of concave mirror of focal length 18cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained? Find the size and nature of the image. Please tell me as soon as possible ​

Answer 1

Given:

$u = -27cm$ ( the object distance should be 27cm)

$f= 18cm$

$h_o = 7cm$

To find:

Nature and size of the image

Solution:

According to the mirror formula , we have ;

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

$\frac{1}{v}=-\frac{1}{18}+ \frac{1}{27}$

$\frac{1}{v}=-\frac{1}{54}$

$v = -54cm$

Therefore , screen should be placed at a distance of 54cm

$\frac{h_i}{h_0}=\frac{v}{u}$

$\frac{h_i}{7}=\frac{54}{-27}$

$h_i = -14cm$

Therefore , height of the image should be 14cm and it will be inverted in nature.