Problem 4 - Olympiad

A convex lens (f = 20 cm) is cut horizontally exactly at its optic axis. The lower half is displaced 0.5 mm downward and the upper half remains fixed. For an axial point object at 30 cm, the number of images formed is

A. 1B. 2C. 3D. 4

Correct: B

Each half-lens forms its own image. Since the halves are separated perpendicular to the optic axis, the images are laterally displaced but lie on the same axial plane; hence two distinct images are observed.