Question

an object place at distance at 12 cm from a convex mirror of focal length 20 cm the distance between an object and its image formed in mirror is​

Answer 1

v=60cm[this is at the centre of curvature of the mirror]

Thus we get the radius of curvature as

v−d=R

60−10=R⇒R=50cm

thus we get the focal length as f=

2

R

=25cm

Answer 2

we know that ,

the focal length of a convex mirror is positive

f=+20cm

image distance is negative as we all the distances are measured from the pole an the object is placed on the negative side on the x axis

u=-12cm

as per mirror formula,

1/f=1/v+1/u

1/20=1/v-1/12

1/20+1/12=1/v

1/v=32/240

v=240/32=7.5 cm

v=7 .5 cm

I hope this helps ( ╹▽╹ )