Question

A convex lens forms an inverted image of size same as that of the object which is placed at a distance 60 cm in front of the lens. Find position of image and focal length of the lens.

Answer 1

If the image is same size as object than image distance is also 60 cm
the same size of object and image is possible at 2f
so the image position is on the 2f
focal length of lens
2f=60cm
f=30cm

Answer 2

answer•position will be 60 cm and gocal lenght will be 30cm

STEP BY STEP SOLUTION

m= height of the image / height of the object =v/u

m=h1/h2 =v/u

h1 is the height of the image which is equal to H2 ( as given in the question)

h1= - h2 ( h2 is in negative because it lies on the opposite side of tye incident ray)

so,

v = -u ( this states that position of the image will be 60 cm)

APPLYING LENSE FORMULA

1/v - 1/u = 1/f

1/ 60 - 1/(-60) = 1/f

1/60 + 1/60 = 1/f

2/60 = 1/f

30 = 1/f

f = 30 cm

Hope it hepls