Question

Find the size, nature and position of image formed when an object of size $1cm$ is placed at a distance of $15cm$ from a concave mirror of focal length $10cm$?

Answer 1

$u=-15$cm

$f=-10$cm

$h=1$cm

From mirror formula

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

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

$\frac{1}{v}=\frac{1}{-10}-\frac{1}{-15}$

$v=-30$cm

The image is formed at a distance $30$cm on the left side of the mirror from the pole.

$m=\frac{h^{\prime }}{h}=\frac{-v}{u}$

$h^{\prime }=-1\times \frac{-30}{-15}$

$h=-2$cm

The image size is $2$cm and it is real and inverted.