Question

the focal length of a concave mirror is 20 cm. Find the position of image of the object kept at a distance of 30
from the mirror.​

Answer 1

Explanation:

Given :

focal length ( f ) = -20 cm

object ( u ) = - 30 cm

Image ( v ) = ?

Mirror Formula :

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

$\frac{1}{ - 20} = \frac{1}{v} + \frac{1}{ - 30}$

$\frac{1}{v} = \frac{1}{30} - \frac{1}{20}$

$\frac{1}{v} = \frac{2 - 3}{60}$

$\frac{1}{v} = \frac{ - 1}{60}$

$v = - 60 \: cm$

Thank you