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What is a Spherical Mirror?-Definition, And Terminologies

August 25, 2022
written by Adeel Abbas

A spherical mirror is a mirror that has the shape of a piece cut out of a spherical surface. The two types of spherical mirrors are the Concave mirror and the convex mirror.

What is a Spherical mirror?

A mirror with a curved reflection surface is called a curved mirror. The surface may be either bulging outward or collapsing inward. The surfaces of most curved mirrors are shaped like part of a sphere, but other shapes can be used in optical devices.

The most common non-spherical type are parabolic reflectors, found in optical devices such as reflecting telescopes that need to image distant objects, since spherical mirror systems, like spherical lenses, suffer from spherical aberration. They have regions where distorted images can be seen. When the object is placed at certain distances, they provide highly magnified or highly diminished images.

Terminologies in Spherical Mirror

There are a few basic terminologies that one needs to know while studying spherical mirrors.

Center of Curvature

At the point in the center of the mirror, the curve of the mirror is the same as it was at that point. That point is called the center of curvature.

Radius of Curvature

The distance between the pole and the center of curvature is called the linear distance.

Principal Axis

The imaginary line goes through the center of the spherical mirror and through the optical center.


The midpoint of the spherical mirror is called a pole.


A mirror’s focal point is the point at which the reflection of light actually happens. The size of the mirror is also given by this.

Principal Focus

A focal point is also referred to as a principal focus. It is on the axis of a mirror or lens were rays of light parallel to the axis appear to converge.


Light rays that are parallel to the principal axis will converge on a point after being reflected from the mirror. it is called focus