Answer:
40 cm
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.
