Question

The picture shows rays passing through an unknown lens.

A grey rectangle with rounded corners labeled Unknown lens has a focal point to its left and a grey arrow to the left of the focal point, pointing up from a line running through the center of the lens. A line from the top of the grey arrow goes straight to the centerline of the lens and then sharply down and right to focal point B. A line from the top of the grey arrow goes shallowly down and right to the centerline of the lens and then straight right to label A. A line from the top of the grey arrow goes straight down and right through the center of the lens to a label D. A line from the top of the grey arrow goes down and right through the left focal point to the centerline of the lens and then straight to a label C.

Which ray would appear on a ray diagram for both a concave lens and a convex lens?

A
B
C
D

Answer 1

D

The ray through the optical center of a thin lens goes undeviated for both convex and concave lenses, so the center ray (D) appears in both ray diagrams.