### Curved Mirror

- A curve is part of a circle. Therefore
- the centre of the circle will also be the centre of the curve and is called the centre of curvature, and
- the radius of the circle will be equal to the radius of the curve, called the curvature radius.

#### Important Terms

Centre of curvature, C |
The geometric centre of a hollow sphere of which the concave or convex mirror is a part. |

Pole of mirror, P |
The centre point on the curved mirror. |

Principal axis |
A line which passes through the centre of curvature, C and the pole of a curved mirror, P. |

Radius of curvature, r |
Distance between the pole, P and the centre of curvature, C. |

Principal focus, F |
A point through which all rays travelling parallel to the principal axis converge to or appear to diverge from after reflection by the mirror. |

Focal length, f |
The distance between the principal focus, F and the pole of the curved mirror, P. |

Aperture of mirror |
The portion of the surface of the mirror that reflects light. |

Object distance, u |
Distance of object from the pole of the mirror, P. |

Image distance, v |
Distance of image from the pole of the mirror, |