Question

an object is placed 10 cm from a converging lens with a focal length of magnitude 20cm. what is the magnification?

Answer 1

Given the focal length f of the converging lens is 20cm and the object distance is u = 10cm. By sign convention f = 20cm and u = -10cm. If v is the image distance, then by lens formula

So the image distance is 20cm from the lens. Since its value is negative, the image is formed on the same side of the object.

The magnification is given by,

So the magnification of the image is 2.