Question

an converging mirror of focal length 20 cm forms an image which is twice the size of the object. Calculate two possible distances of the object from the mirror

Answer 1

Given f = - 20 cm h1 = 2h0 where h1 denotes image height and h0 denotes object height

Now m = -v /u = h1/h0
= -v/u = 2h0/h0
= -v/u =2
= v = -2u eq 1

By using mirror formula we have
1/f = 1/v + 1/u
1/-20 = 1/u - 1/2u. ( beacuse v = -2u)
1/-20 = 1/2u
on taking reciprocals both side
-20 = 2u
-10 = u

Putting this value in equation 1
v = - (-20)
v = 20

Hope it will be helpful...

Answer 2

hope it helps you to understand the concept