At what distance should an object be placed from a lens of focal length 25 cm to obtain its image on a screen placed on the other side at a distance of 50 cm from the lens? What will be the magnification produced in this case?

Given that,

Focal length f = 25 cm, Image distance u = 50 cm.

From the lens formula,

The object must be placed 50 cm away from the lens on the other side to produce a magnification of -1.