A lens that is thicker in the center than at the edges

A lens that is thicker in the center than at the edges

• A. Convex Lens
• B. Concave Lens
• C. Plano Lens
• D. Spherical Lens

Answer: (A)

A lens that is thicker in the center than at the edges is a convex (converging) lens. Its outward-curved surfaces bend incoming light toward the center, so parallel rays are brought together at a focal point on the other side. This property—central thickening causing rays to converge—is what defines a convex lens. A concave lens is thinner in the middle and spreads light apart. A plano lens has one flat side, and a spherical lens describes curved surfaces but doesn’t specify the center being thicker, so neither guarantees the convergence described by the thicker-center shape.

A lens that is thicker in the center than at the edges is a convex (converging) lens. Its outward-curved surfaces bend incoming light toward the center, so parallel rays are brought together at a focal point on the other side. This property—central thickening causing rays to converge—is what defines a convex lens. A concave lens is thinner in the middle and spreads light apart. A plano lens has one flat side, and a spherical lens describes curved surfaces but doesn’t specify the center being thicker, so neither guarantees the convergence described by the thicker-center shape.