# Terms Associated With Spherical Mirrors.

Q13.Explain the terms associated with spherical mirrors.

Ans.

• Pole: The center of the reflecting surface of a spherical mirror is a point which is called as the pole.
It lies on the surface of the mirror and is represented by the letter capital ‘P’.
• Aperture: The diameter of the reflecting surface of spherical mirror is called its aperture.
• OR
• The effective width of the spherical mirror from which reflection of the light can take place is called its aperture. Its aperture of mirror represents the size of the mirror.
• Center of Curvature: The geometric center of the hollow sphere of which the spherical mirror is a part, is called the center of curvature of a spherical mirror. It is denoted by letter ‘C’. It lies outside the reflecting surface.In a concave mirror, it lies in front of the mirror.In a convex mirror, it lies behind the mirror.
• Radius of Curvature: The radius of the hollow sphere of which the reflecting surface of the spherical mirror is a part, is called the radius of curvature.It is the distance between the pole and the cent re of curvature of the spherical mirror; it is denoted by capital ‘R’.
• Principal Axis: The straight line passing through the center of curvature and the pole of the spherical Mirrors called is its principal axis. It is normal to the mirror at its pole.