23.1 Reflection
pp. 498 - 502
Mr. Richter
Agenda
 Warm-Up
 Review HW
 Notes
 Optics and Mirrors
 Reflection
 The Law of Reflection
Objectives: We Will Be Able To…
 Describe the behavior of images in mirrors.
 Define reflection, and distinguish between types of
reflection.
 Understand the law of reflection.
Warm-Up:
 Why does a mirror seem to switch or flip images from left to
right, but doesn’t switch images upside down?
Optics and Mirrors
Optics and Mirrors
 Optics is the study of light.
 An optical device is something that
purposefully changes the direction
of light.
 Mirrors are optical devices that
reflect light.
 A good mirror reflects about 90% of
the light that hits it.
Optics and Mirrors
 Flat mirrors reflect an image
that is identical to the object.
 Curved mirrors can distort an
image, and make it larger or
smaller.
Reflection
Reflection (in Flat Mirrors)
 In flat mirrors, the image appears to be the same distance
from the mirror as the object.
 Mirrors reverse front to back, not left to right.
Reflection
 If a surface is smooth, all of
the reflected light heads in
the same direction. This is
called specular reflection.
 If a surface is rough, the
reflected light heads in
many different directions.
This is called diffuse
reflection.
 We see most objects by
diffuse reflection.
Reflection
Reflection
 Sometimes reflection can be both specular and diffuse.
The Law of Reflection
and Ray Diagrams
Ray Diagrams
 The incoming ray of light is
called the incident ray.
 The reflected ray of light is
called… the reflected ray.
 The line that is perpendicular
to the mirror (or any surface) is
called the normal line.
The Law of Reflection
 The law of reflection states
that the angle of incidence
(incoming light) is equal to
the angle of reflection
(outgoing light).
 Angles are always measured
from the normal line.
Wrap-Up: Did we meet our objectives?
 Describe the behavior of images in mirrors.
 Define reflection, and distinguish between types of
reflection.
 Understand the law of reflection.
Homework
 p. 502 #3, 4
 p. 519 #1-4