Center of curvature

The osculating circle to the curve is centered at the centre of curvature.

Cauchy defined the center of curvature C as the intersection point of two infinitely close normal lines to the curve.

This term is generally used in physics regarding the study of lenses and mirrors (see radius of curvature (optics)).

[2][page needed] It lies on the principal axis of a mirror or lens.

[3] In case of a convex mirror it lies behind the polished, or reflecting, surface and it lies in front of the reflecting surface in case of a concave mirror.