Define the terms pole, principal axis and center of curvature with reference to a spherical mirror.

Hint The above problem is based on the concept of the geometry of the optical devices and behavior of the light in the optical device. The light gets reflected from the optical device. The size and shape of the image is decided by the geometry of the optical device.

Complete step by step answer
The spherical mirror is formed by the cutting of a sphere from a large piece of the mirror. The spherical mirrors are of two types. First is the Concave mirror and second is the convex mirror.
The center of curvature is defined as the center of the sphere by which the spherical mirror is formed. The pole is the midpoint of the concave or convex mirror. The line between the center of curvature and pole is called the principal axis.

Additional Information The principal focus of the spherical mirror lies on the principal axis and located at the midpoint of pole and center of curvature. The distance between the pole and principal focus is called the focal length of the spherical mirror. The light always passes from the principal focus of the spherical mirror. The focal length is always the half of the radius of the spherical mirror.

Note The distance of the object and its image remain always the same from the pole of the spherical mirror. If the spherical mirror is rotated from its initial position then the image of the object rotates two times the rotation of the mirror.