Question

at what distance from a converging lens of focal length 12cm must an object be placed in order that an image of magnification 1 will be produced?​

Answer 1

24cm

Explanation:

magnification would be -ve 1

so

v=-u

1/f=1/v-1/u

1/-12=1/u+1/u

1/-12=2/u

u=24cm

also at 2f1 and 2f2 the magnification of a convex lens is zero

so2fi=2×fi=2×12=24

Answer 2

Answer:- Object distance is 24 cm.