Which shape describes where the lens bulges outward?

The shape that describes where the lens bulges outward is convex. Convex lenses are thicker in the middle and taper toward the edges, causing light rays to converge when they pass through the lens. This property is utilized in various applications, such as in magnifying glasses, cameras, and eyeglasses for farsightedness.

In contrast, spherical refers to a three-dimensional shape that can be either convex or concave, depending on how it curves. Cylindrical pertains to a shape with a particular geometry that extends in one direction, typically characterized by a circular cross-section, which does not describe a lens that bulges outward. Concave shapes, on the other hand, curve inward and cause light to diverge rather than converge, making them the opposite of convex shapes. Thus, convex is the appropriate choice for describing lenses that bulge outward.