A projection lantern is used to give the image of a slide on a screen. If the image is 24 times as large as the slide and the screen is 72.0m from the projecting lens, what is the position of the slide from the lens?

A. 0.3m
B. 3.0m
C. 3.5m
D. 4.0m

Correct Answer:

Option B – 3.0m

Explanation

V = 72m
U = Magnification = 24
But Magnification = V/U
∴ 24 = 72/U
U = 72/24
U = 3.0m