Question

In order to form an image with a converging lens that is the same size as the object, how far away from the lens should the object be placed?

Answer 1

An object placed at a distance 2f from the lens forms an image at a distance 2f from lens on other side

here f is focal length

magnification = s'/s = 2f/2f = 1

mafnification = h'/h

1= h'/h

h' = h

So object is placed at distance 2f.