# Determine the radius of curvature of a convex or concave spherical surface by spherometer

## Determine the radius of curvature of a convex or concave spherical surface by spherometer

Radius of curvature:

The distance from the center of a circle or sphere to its surface is its radius. For other curved lines or surfaces, the radius of curvature at a given point is the radius of a circle that mathematically best fits the curve at that point.

The equivalent “surface radius” that is described by radial distances at points along a body’s surface is its radius of curvature (more formally, the radius of curvature of a curve at a point is the radius of the osculating circle at that point). With a sphere, the radius of curvature equals the radius (thus, radius of curvature is sometimes used as a synonym for radius). With an oblate ellipsoid (or, more properly, an oblate spheroid), however, not only does it differ from the radius, but it varies, depending on the direction being faced. The extremes are known as the principal radii of curvature.

### Determine the radius of curvature of a convex or concave spherical surface by spherometer

**Determine the radius of curvature of a convex or concave spherical surface by spherometer**

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*Determine the radius of curvature of a convex or concave spherical surface by spherometer*

Determine the radius of curvature of a convex or concave spherical surface by spherometer

Determine the radius of curvature of a convex or concave spherical surface by spherometer