What is the centre of the reflecting surface of a spherical mirror known as? 

The Correct answer is Pole.

Key Points

• The pole of a spherical mirror is the geometric centre of the mirror's reflecting surface.
• The pole is represented by the symbol P in ray diagrams.
• It is the point on the mirror where the principal axis meets the mirror.
• The principal axis is an imaginary line that passes through the pole and the centre of curvature of the mirror.
• Spherical mirrors can be either concave or convex, and the pole is a critical reference point for constructing ray diagrams in both types of mirrors.
• Understanding the pole is essential for determining the nature and position of the image formed by spherical mirrors.

 Additional Information

• Centre of curvature
  • The centre of curvature of a spherical mirror is the centre of the sphere from which the mirror is a part.
  • It is represented by the symbol C and lies outside the mirror surface.
  • For a concave mirror, the centre of curvature lies in front of the mirror, while for a convex mirror, it lies behind the mirror.
• Principal axis
  • The principal axis is an imaginary straight line that passes through the pole and the centre of curvature of the mirror.
  • It is used as a reference line in ray diagrams to determine the path of light rays reflecting off the mirror.
• Radius of curvature
  • The radius of curvature is the distance between the pole and the centre of curvature of the mirror.
  • It is denoted by the symbol R and is twice the focal length (R = 2f) of the mirror.