Which lens produces a real image when the object is placed beyond the focal length?

• A. Concave lens
• B. Convex lens
• C. Both
• D. Neither

Answer: (B)

Real images form only when light rays actually converge to a point on the opposite side of the lens. A convex lens is a converging lens, so when the object is placed beyond its focal length, the refracted rays cross and produce a real, inverted image on the far side. A concave lens causes rays to diverge, so they don’t meet to form a real image of a real object; the image is virtual and upright on the same side as the object. Therefore, beyond the focal length, the convex lens is the one that can produce a real image.