What is the primary function of a spherometer?

The primary function of a spherometer is to measure the radius of curvature of curved surfaces. This instrument is particularly useful in optical applications, where determining the curvature of lenses or mirrors is essential for understanding how they will bend light.

A spherometer consists of a circular base with three legs to stabilize it and a central screw that can be adjusted. When the spherometer is placed on a curved surface, the height difference measured by the screw allows for the calculation of the radius of curvature. This is crucial in fields such as optics, physics, and engineering, where precise curvature measurements impact the efficacy of lenses and mirrors.

The other options relate to measurements not pertinent to a spherometer's function. Instruments designed to measure weight, volume, or temperature serve different purposes and utilize different mechanisms tailored to their specific measurements. Thus, the option that describes the function of a spherometer accurately reflects its design and application in practice.