Question

if a concave mirror of focal length 10 cm forms an image at a distance of 20 CM calculate the distance of object from the mirror.

Plz ans it GUYS​

Answer 1

Here f ( focal length ) = - 10 cm ,

v ( image distance ) = - 20 cm

To find : u = object distance = ?

Using mirror formula ,

$\frac{1}{u} + \frac{1}{v} = \frac{1}{f} \\ = > \frac{1}{u} = \frac{1}{f} - \frac{1}{v} \\ = > \frac{1}{u} = \frac{v - f}{vf} \\ = > u = \frac{vf}{v - f} = \frac{( - 20)( - 10)}{( - 20) - ( - 10)} \\ = > u = \frac{( - 20)( - 10)}{ - 20 + 10} = \frac{( - 20)( - 10)}{( - 10)} \\ = > u = - 20 \: cm$

Hope this help....