Question

Find the size, nature & position of image formed when an object of size 1cm is
placed at a distance of 12cm from a concave mirror of focal length 10cm.

Answer 1

Object size = $h_o$ = 1 cm.

Object distance = $u$ = - 12 cm.

Focal length = $f$ = - 10 cm.

We know,

$\boxed{\dfrac{1}{f} = \dfrac{1}{v} + \dfrac{1}{u}}$

So, with sign convention we put the values:-

- 1/10 = 1/v - 1/12

=> 1/v = - 1/10 + 1/12

=> 1/v = (- 6 + 5)/(60)

=> 1/v = - 1/60

=> v = - 60 cm.

So, $m = - \dfrac{v}{u}$ = - 5.

Therefore, a real, inverted, enlarged, image is formed and the position of the image is formed beyond C.

More:-

Relationship between m, f and u:-

$m = \dfrac{f }{f-u}$

Relationship between m, f and v:-

$m = \dfrac{f-v}{f}$