Spherical mirrors are mirrors whose surfaces form a part of a hollow sphere, The spheres can be made of glass or any polished metal surfaces. A spherical mirror is a mirror which has the shape of a piece cut out of a spherical surface. There are two types of spherical mirrors: concave, and convex. Convex mirror :. If the mirror coating is in the inside of the spherical surface, then the mirror is called a convex mirror. Concave mirror :If the mirror coating is on the outside of the spherical surface, then the mirror is called a concave mirror.