Question

A cell phone is placed 40 cm in front of a converging lens with a focal length of magnitude 20 cm. How far is the image of this phone from the lens?

Answer 1

40 cm

Step-by-step explanation:

Given that:

The cell phone is placed at a distance u = 40 cm

focal length f = +20 cm

image distance = v

from lens equation

1/u + 1/v = 1/f

1/40 + 1/v = 1/20

1/v = (1/20) - (1/40)

v = (20*40)/(40-20)

v = 40 cm

We can therefore conclude that: since we have a positive value for he image , the image is real and the image size is the same as the object.