Question

An optical device Y has positive focal length. Y is?

• A. either a concave lens or a concave mirror
• B. either a convex lens or a convex mirror
• C. either a convex lens or a concave mirror
• D. either concave lens or a convex mirror

Answer 1

Answer:

B. either a convex lens or a convex mirror

Optical devices with positive focal lengths focus light rays rather than diverge them. Both convex lenses and convex mirrors have positive focal lengths, making them suitable candidates for device Y.