Lesson: Chapter 5 — Optics

5.2. Curved (spherical) mirrors 3 of 4

Pole, centre of curvature and principal axis

A spherical mirror is a piece cut from an imaginary sphere. Three things about it are named.

A concave mirror with its pole P, the focus F and the centre of curvature C marked along the principal axis.

Centre of curvature (C)

The centre of the sphere the mirror is part of.

Pole (P)

The exact middle point of the mirror's face.

Principal axis

The line through the pole and the centre of curvature. It meets the mirror at right angles at P.