Question

an object is placed at a distance of 12 cm from a concave mirror its image formed at a distance of 24cm . what will be the magnification​

Answer 1

Answer:

-2

Explanation:m= -v/u=24/-12=-2

Answer 2

Answer:

f = -8cm

Explanation:

Image is inverted so magnification ratio should be negative.

Since the object size is double so magnification ratio m=−2

now the object distance from mirror  u=−12

So m  = $-\frac{v}{u}$

-2 = $\frac{v}{-12}$

$v= -24cm$

Image is formed at 24 cm from mirror in same direction of object.

Now be know

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

$\frac{1}{f} = \frac{1}{-24} +\frac{1}{-12}\\\\f = -8cm$