Curved Mirrors Sections 11.5 & 11.6

Types of Mirrors There are three basic types of mirrors: plane, concave, and convex Light rays behave differently when they reflect from curved mirrors as opposed to plane mirrors

Concave Mirror…. AKA Converging Mirror Used in makeup and shaving mirrors as well as in flashlights, spotlights, and car headlights to help make an intense, focused beam of light f PA F Principal axis: a line through the centre of the mirror that includes the principal focus Principal focus (AKA focal point): where reflected parallel light rays come together (labeled F) Focal length: the distance from the principal focus to the middle of the mirror (labeled f)

Concave Mirrors The image formed by concave mirrors depends on how far the object is from the focal point A - if it is far from the focal point, the image is smaller than the object, inverted (upside down), and real (appears in front of the mirror, can be placed on a screen) B - as the object approaches the focal point, the image becomes larger but is still inverted and real C - if it is between the focal point and the mirror, the image is larger than the object, upright, and virtual (appears to be behind the mirror, cannot be placed on a screen)

Light Ray Rules for Concave Mirrors A light ray parallel to P.A. reflects through F. A light ray that passes through F will reflect parallel to P.A. A light ray hitting the vertex (perpendicular to P.A.)

Convex Mirrors… AKA Diverging Mirror What does a convex mirror look like? A convex mirror is a mirror that curves outward, like the outside of a spoon Used in security as well as rearview and side-view mirrors because its curvature reflects light from a large area to your eye (gives a wide view) Parallel light rays bounce off the surface of the mirror and spread apart (diverge) as if they came from a focal point behind the mirror The image formed by convex mirrors is always smaller than the object, upright, and virtual, no matter where the object is located

Convex Mirror f PA F Principal axis: a line through the centre of the mirror that includes the principal focus Principal focus (AKA focal point): where reflected parallel light rays come together (labeled F) Focal length: the distance from the principal focus to the middle of the mirror (labeled f)

Which mirror is convex and which is concave? The mirror on the left must be concave – larger and inverted The mirror on the right must be convex – smaller and upright

A Summary of Mirrors