What type of lens is thinner at the center than at the edges?

A lens that is thinner at the center than at the edges is characterized as a concave lens. This type of lens diverges light rays that pass through it, causing them to spread out. When parallel rays of light enter a concave lens, they bend outward, and if imagined extended backward, they appear to originate from a focal point located on the same side of the lens as the incoming light.

Concave lenses are often used in devices such as glasses for nearsightedness, where correcting the focal length so that images properly focus on the retina is necessary. The shape of a concave lens, being thinner in the middle and thicker at the edges, facilitates this divergence of light rays, making it essential in various optical applications.

In contrast, a convex lens, which is thicker at the center than at the edges, converges light rays, bringing them to a focal point on the opposite side of the lens. A cylindrical lens has a different profile, designed to focus light in only one direction and is typically used to correct astigmatism. Consequently, the option that correctly identifies a lens thinner at the center than at the edges is the concave lens.