Question

When an object is placed at a distance of 60 cm from a convex mirror the magnification producedis 1/2 . Where should the object be placed to get a magnification of 1/3?

Answer 1

Let u=object distance

v=image distance

f= focal length

1st case> u=60cm

magnification= m=v/u

⇒v=60/2=30cm

we know,1/f=1/v+1/u

f=60cm

case-2>m=1/3=f/u-f

⇒u=4f=240cm

Hence to find an image of magnification 1/3 the object should be placed at a distance of 240cm from the convex mirror.