When does lens convexity increase?

Lens convexity increases when:

1. Decreased Radius of Curvature:

- The radius of curvature (ROC) is the distance between the center of curvature and the vertex of the lens.

- When the ROC decreases, the lens becomes more curved and, therefore, more convex.

2. Increased Refractive Index:

- The refractive index (n) of a material is the ratio of the speed of light in a vacuum to the speed of light in that material.

- When the refractive index increases, the bending of light rays at the lens surfaces increases, resulting in greater convexity.

In other words, lens convexity is directly proportional to the curvature of its surfaces and the refractive index of the lens material.