Lesson 1: Reflection of Light at Curved Surfaces

This lesson covers the fundamental properties and definitions associated with light reflection when interacting with curved or spherical mirror surfaces.

The study of curved mirrors requires a precise understanding of the geometric and optical points that define the mirror's structure and behavior.

Centre of Curvature: A spherical mirror is essentially a slice or a part of a much larger imaginary sphere. The centre of curvature is defined as the centre of that sphere of which the mirror is a part.
Radius of Curvature: This is defined as the radius of the sphere of which the mirror is a part.
- In practical measurement, the radius of curvature is equal to the distance between the pole ( $P$ ) and the centre of curvature.

Principal Axis: This is the imaginary straight line that passes through both the pole ( $P$ ) and the centre of curvature. It serves as the primary reference line for calculating angles of incidence and reflection.
Pole ( $P$ ): The pole ( $P$ ) is defined as the specific point located at the geometric middle of the mirror's curved surface.

Focus: The focus is a critical point on the principal axis determined by the behavior of reflected light rays.
- When rays coming from an object travel parallel to the principal axis, they undergo reflection at the mirror surface.
- After reflection, these rays seem to cross the principal axis at nearly the same point.
- More formally, the focus of the mirror is the specific point where the reflected rays either actually converge (meet) or appear to diverge from (spread out).