Question

if an object is held at a distance of 60cm from a convex mirror of focal length 20cm.At what distance from the convex mirror should a plane mirror be held so that the image of two mirror is coincide

Answer 1

Given that,

Object distance u = –60 cm

then

⇒ V = 30 cm.

Now use mirror formula to find its focal length (f)

Again from question:-

Let object distance = –x

Then by using the mirror formula

Hence the required object distance = 120 cm

Answer 2

The answer will be 22 . 5 cm 1/f=1/v+1/u 1/20==1/v-1/60 v=15 cm so the distance between object and image is 60+15=75 cm so mirror should be placed at 75/2=37.5 cm away from object 60-37.5=22.5 cm Hope it helps..!!