12.2 SPHERICAL MIRRORS
A mirror whose polished, reflecting surface is a part of a hollow sphere of glass or plastic is called a spherical mirror. In a spherical mirror, one of the two curved surfaces is coated with a thin layer of silver followed by a coating of red lead oxide paint. Thus, one side of the spherical mirror is opaque and the other side is a highly polished reflecting surface. Depending upon the nature of reflecting surface, there are two types of spherical mirrors as shown in Fig.12.4.
Concave Mirror: A spherical mirror whose inner curved surface is reflecting is called concave mirror. In concave mirror the size of the image depends on the position of the object. Both virtual and real images can be formed by a concave mirror.
Convex Mirror: A spherical mirror whose outer curved surface is reflecting is called convex mirror. In convex mirror the size of the image is always smaller than the object. Only virtual and erect image is formed by a convex mirror.
Pole: It is the midpoint of the curved surface of spherical mirror. It is also called vertex.
Centre of Curvature (C): A spherical mirror is a part of a sphere. The centre of this sphere is called centre of curvature.