Question

If a magnification of, -1 is to be obtained by using a converging lens of focal length 12 cm, then the object must be placed : (a) within 12 cm (b) at 24 cm (c) at 6 cm (d) beyond 24 cm

Answer 1

Option b at 24cm

Here magnification is negative so inverted and real
and 1 so the equal size of image and object
both satisfied when an object at 2F
that is $2\times 12$ = 24