A convex lens of focal length 8.0cm produces a real image magnified 2 times...please help...?

Question

A convex lens of focal length 8.0cm produces a real image magnified 2 times. Where is the object located? Where is the image located? Show your working.

Answer 1

u = object distance,

v = image distance.

v / u = 2

u = v / 2

1 / u + 1 / v = 1 / 8

Substituting for u:

2 / v + 1 / v = 1 / 8

3 / v = 1 / 8

v = 24 cm. from the lens, on the side opposite from the object.