Chapter 10–>Light; Reflection and Refraction

A mirror (or any polished, reflective surface) with a curvature is known as a curved mirror.

Pole (P): The midpoint of a spherical mirror.
Centre of curvature (C): The centre of the sphere that the spherical mirror was a part of.
The radius of curvature (r): The distance between the centre of curvature and the spherical mirror. This radius will intersect the mirror at the pole (P).
Principal Axis: The line passing through the pole and the centre of curvature is the main or principal axis.
Concave Mirror: A spherical mirror with the reflecting surface that bulges inwards.
Convex Mirror: A spherical mirror with the reflecting surface that bulges outwards.
Focus (F): Take a concave mirror. All rays parallel to the principal axis converge at a point between the pole and the centre of curvature. This point is called as the focal point or focus.
Focal length: Distance between pole and focus.