The line passing through the center of the sphere and attaching to the mirror in the exact center of the mirror is the principal axis.
The point in the center of the sphere from which the mirror was sliced is known as the center of curvature and is denoted by the letter C .
Sometimes a figure of 2F is used at this point.
The point on the mirror's surface where the principal axis meets the mirror is known as the vertex - V. The vertex is the geometric center of the mirror.
Midway between the vertex and the center of curvature is a point known as the focal point or principal focus ; the focal point is denoted by the letter F. The following facts are used to construct ray diagrams: |