Homework SourseHow far from a converging lens with a focal length of 25 cm
How far from a converging lens with a focal length of 25 cm should an object be placed to produce a real image which is the same size as the object?
Solution
magnification m = 1
focal length f = 25 cm
object distance = d0
image distance = di
m = - di / do
1 = - di / do
di = - do
and 1/f = 1/di - 1/do
1/25 = 1/( - do) - 1/do
1/25 = - 2/do
=> do = - 50 cm
here - ve sign is due to sign convention which means that the object is situated to the left ( or on the other side of image)
do = 50 cm
