Overview
This lecture explains the three main types of mirrors—plane, concave, and convex—detailing their properties, uses, and key terms related to spherical mirrors.
Types of Mirrors
- There are three types of mirrors: plane, concave, and convex.
- Plane mirrors have flat surfaces and show images of the same height and upright.
- Concave mirrors are curved inward (like the inside of a spoon) and can show inverted or magnified images depending on distance.
- Convex mirrors are curved outward (like the back of a spoon) and always show smaller, upright, and diminished images.
Daily Uses of Mirrors
- Plane mirrors are used for general reflection, such as in bathrooms and elevators.
- Concave mirrors are used as shaving mirrors and can magnify faces.
- Convex mirrors are used for rearview and side mirrors in vehicles and at road intersections for a wider field of view.
Spherical Mirrors: Structure and Function
- Spherical mirrors are sections of a sphere and include both concave and convex mirrors.
- Concave mirrors have a shiny, hollowed surface; convex mirrors have a shiny, bulging surface.
- Concave mirrors converge (focus) parallel light rays to a point (converging mirror).
- Convex mirrors diverge parallel light rays outward (diverging mirror).
- The laws of reflection apply equally to both plane and spherical mirrors; the curvature causes their differing behaviors.
Important Terms for Spherical Mirrors
- Center of curvature (C): Center of the sphere from which the mirror is a part.
- Pole (P): Center of the mirror's surface.
- Radius of curvature (R): Radius of the sphere that forms the mirror.
- Principal axis: Straight line through the center of curvature and pole.
- Aperture: The part of the mirror that reflects light.
- Focus (F): Point where reflected rays converge (concave) or appear to diverge from (convex).
- Focal length (f): Distance between the pole and focus, f = R/2.
Key Terms & Definitions
- Plane mirror — Flat mirror reflecting upright images of the same size.
- Concave mirror — Curved inward, forms real or magnified images.
- Convex mirror — Curved outward, forms upright, diminished images.
- Center of curvature (C) — The geometric center of the sphere.
- Pole (P) — The midpoint of the mirror surface.
- Principal axis — Main line passing through C and P.
- Focus (F) — Point where rays converge/diverge.
- Focal length (f) — P to F distance, equal to half the radius of curvature.
Action Items / Next Steps
- Identify and observe different types of mirrors in your daily life (e.g., torch, dentist's mirror, street mirrors).
- Answer the three top questions from the lecture.
- Review labeled diagrams of concave and convex mirrors.