An object 4 cm tall is placed in front of a convex lens. It produces an image 3 cm tall. What is the magnification of the lens?
12
0.75
1.33
m = h'/h = 3/4 = 0.75
An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens.