Question

The image of an object formed by a mirror is real and inverted and is of the magnification - 1. If the image is at the distance of 30 cm from the mirror. Where is the object placed? Find the position of the image if the object is now moved 20 cm towards the mirror. What is the nature of the image obtained?

Answer 1

given

case(i)                                              

m=-1 ,v=-30 cm

u=?

m=-v/u

-1=30/u

u=-30

1/f=1/v+1/u= 1/-30 + 1/-30=-2/30

∴f=-15

case(ii)

f=-15

u=30-20=10

1/v=1/f-1/u

    =1/-15-(1/-10)

       =1/30

∴v=30

image formed is virtual and erect