REFLECTION AND
MIRRORS
WAVE PROPERTIES
OF LIGHT
Reflection: occurs when a wave
strikes an object and “bounces”
off.
ALL waves show reflection.
SPECULAR REFLECTION
Light reflected off a smooth
or shiny surface is reflected
in one direction. This is
specular reflection.
DIFFUSE REFLECTION
Light reflected off a rough
surface is reflected in many
directions.
LAW OF REFLECTION
states that the angle of incidence is
equal to the angle of reflection.
Normal: is a line perpendicular
to the surface of the mirror.
Incident Ray: is the ray of light
that is striking the mirror.
Reflected Ray: is the ray of light
that bounces off the mirror.
Angle of Incidence: is the angle
between the normal and the
incident ray.
Angle of Reflection is the angle
between the normal and the
reflected ray.
LAW OF REFLECTION
All mirrors obey the Law of Reflection.
It does not matter the shape of the
mirror, the angle of reflection will still
equal the angle of incidence.
MIRROR CHARACTERISTICS
Real or Virtual
Real images can project on a
screen
Virtual images can only be seen
in a mirror
MIRROR CHARACTERISTICS
Upright or Inverted
Upright images are oriented the
same as the object
Inverted images are oriented in
the opposite direction as the
object
MIRROR CHARACTERISTICS
Reduced or Enlarged
Reduced images are smaller in
size than the object
Enlarged images are larger in
size than the object
PLANE MIRROR
PLANE MIRROR
CHARACTERISTICS
•Upright image
•Virtual image
•Same size
•Image distance equal object
distance
•Right and left are changed
PLANE MIRROR
CHARACTERISTICS
CURVED MIRROR
CONCAVE MIRROR
Concave mirrors have
surfaces that curve inward
in the center. Example the
shaving and make-up
mirrors.
Principal Axis (Optical Axis)
Is the straight line drawn through
the center of the mirror.
O
O
O – Center of the mirror
F – Focus of the Mirror
C – Center of Curvature
O
f – Focal Length = distance O to F
R – Radius of Curvature = 2f =
distance O to C
Parallel Light Rays
All light rays parallel to the principal
axis are reflected through the
focus or focal point.
CONCAVE MIRROR
RAY DIAGRAM RULES
1. Any ray parallel to the
principal axis passes through
the focus after striking the
mirror
C
F
O
CONCAVE MIRROR
RAY DIAGRAM RULES
2. Any ray going through C
passes through C after striking
the mirror.
C
F
O
CONCAVE MIRROR
RAY DIAGRAM RULES
3. Any ray passing through F is
reflected parallel to the principal
axis.
C
F
O
OBJECT BETWEEN MIRROR AND F
C
F
O
OBJECT BETWEEN MIRROR AND F
Image Characteristics:
Upright
Enlarged
Virtual
Ex: shaving and make-up
mirrors
OBJECT BETWEEN MIRROR AND F
OBJECT AT F
C
F
O
OBJECT AT F
Characteristics of the Image:
No Image is formed
Ex: Used in Car Headlights
and Flashlights
OBJECT BETWEEN F AND C
C
F
O
OBJECT BETWEEN F AND C
Characteristics of the Image:
Inverted
Enlarged
Real
OBJECT BETWEEN F AND C
OBJECT BETWEEN F AND C
OBJECT AT C
C
F
O
OBJECT AT C
Characteristics of the Image:
Inverted
Same Size as Object
Real
OBJECT AT C
OBJECT BEYOND C
C
F
O
OBJECT BEYOND C
Characteristics of the Image:
Inverted
Reduced
Real
OBJECT BEYOND C
CONVEX MIRROR
Convex mirrors are curved
outward. It is like the back
of a spoon.
F – Focus of the Mirror- of Focal
Point is the point where the
parallel rays appear to diverge
from
Parallel Light Rays
Light rays parallel to the optical
axis are all reflected and appear
to be coming from behind the
mirror from a point called the
focus or focal point.
F
CONVEX MIRROR
RAY DIAGRAM RULES
1. Any ray parallel to the optical
axis appears to reflect from the
focal point behind the mirror
O
F
CONVEX MIRROR
RAY DIAGRAM RULES
2. Any ray that appears to go
through F behind the mirror is
reflected parallel
F
C
CONVEX MIRROR
RAY DIAGRAM RULES
3. Any ray that appears to go
through C behind the mirror is
reflected the same.
F
C
OBJECT BETWEEN MIRROR AND F
C
F
F
C
OBJECT BETWEEN MIRROR AND F
Characteristics of the Image:
Upright
Reduced
Virtual
Ex: Used in Stores
OBJECT PLACED AT F
C
F
F
C
OBJECT PLACED AT F
Characteristics of the Image:
Reduced
Upright
Virtual
Ex: Used in Stores
OBJECT BETWEEN F AND C
C
F
F
C
OBJECT BETWEEN F AND C
Characteristics of the Image:
Reduced
Upright
Virtual
Ex: Used in Stores
OBJECT AT C
C
F
F
C
OBJECT AT C
Characteristics of the Image:
Reduced
Upright
Virtual
Ex: Used in Stores
OBJECT BEYOND C
C
F
F
C
OBJECT BEYOND C
Characteristics of the Image:
Reduced
Upright
Virtual
Ex: Used in Stores
MIRRORS
MIRROR EQUATIONS
M = magnification
hi = height of Image
ho = height of Object
di = Distance of Image from mirror
do = Distance of Object from mirror
f = focal length
MIRROR EQUATIONS
f is negative if convex mirror
di is negative - image is virtual and
formed behind the mirror
di is positive - image is real and
formed in front of the mirror
MIRROR EQUATION
hi is negative if image is inverted
M<1 the image is smaller than the
object
M>1 the image is larger than the
object.