What describes a diverging lens?

A diverging lens is characterized by being thick at the edges and thin in the middle. This shape causes parallel rays of light that enter the lens to diverge, or spread out, after passing through it. The point at which these rays appear to come from is called the focal point, and for a diverging lens, this focal point is virtual, meaning it cannot be reached by actual light rays but is rather a point from which the light appears to emanate.

In contrast, a lens that is thin at the edges and thick in the middle is a converging lens, which focuses light to a real focal point on the opposite side of the lens. Equal thickness across the lens would describe a plano-convex or plano-concave lens, which do not fit the description of a diverging lens. A lens that is curved on both sides can describe both converging and diverging lenses, but the critical determining factor for a diverging lens is its thickness profile, specifically being thicker at the edges than in the center. Thus, the description of a diverging lens hinges on its thicker edges and thinner center, accurately aligning with the nature of how it manipulates light.