CURVED Mirrors
CONCAVE AND CONVEX
MIRRORS
USES
• FLASHLIGHT
• HEADLIGHT OF CAR
• SEARCH LIGHT
• MAKE UP MIRROR
• SATELLITE DISH
The Anatomy of a Curved Mirror
Curved mirrors are created when you make
part of the surface of a sphere reflective.
• CONCAVE
• REFLECTION ON INNER SURFACE
OF SPHERE
• aka Converging mirror
CONVEX
• REFLECTION ON OUTERSURFACE
OF SPHERE
• aka Diverging Mirror
TERMINOLOGY OF
CONCAVE MIRRORS
PRINCIPAL AXIS
Line passing through the center of the sphere and attaching to the
mirror in the exact center of the mirror;
CENTRE OF CURVATURE
The point in the center of sphere from which the mirror was
sliced;
VERTEX (A)
Point on the mirror’s surface where the
principal axis intersects the mirror;
RADIUS OF CURVATURE (R)
The distance from the vertex to the center of curvature
FOCAL LENGTH (f)
The distance from the mirror to the focal point
The focal length is one-half the radius of curvature.
FOCAL POINT
FOCAL POINT (F)
• Midway between the vertex and the center of
curvature;
• Point in space at which light incident towards
the mirror and travelling parallel to the
principle axis will meet after reflection;
RULES OF REFLECTION FOR
CONCAVE MIRRORS
•
•
•
•
A light ray parallel to the principal axis is
reflected through the focus.
A light ray through the Centre of
Curvature is reflected back onto itself.
A ray through the Focus will reflect
parallel to the principal axis.
A ray aimed at the Vertex will follow the
law of reflection.
Ray Diagrams - Concave Mirrors
An object is located beyond the center of
curvature (C) of a concave mirror:
1. Pick a point on the top of the object
and draw two incident rays (1parallel
to the principal axis and the other
through the focal point) traveling
towards the mirror.
2. Reflect those rays according to the
Rules of Reflection for concave
mirrors:
3. Mark the image of the top of the object:
4. Repeat the process for the bottom of
the object:
Ray Diagram for Object located at C
Ray Diagram for Object located between C and F
IMAGE (REAL OR VIRTUAL)
In the case of the object being located
beyond C, the case of the object being
located at C, and the case of the object
being located between C and F a
REAL IMAGE is formed.
Ray Diagram for Object located in front of F
Ray Diagram for Object located at F
Two Rules of Reflection for Concave
Mirrors
1. Any incident ray traveling parallel to the
principal axis on the way to the mirror will
pass through the focal point upon
reflection.
2. Any incident ray passing through the focal
point on the way to the mirror will travel
parallel to the principal axis upon reflection.