Reflection & Mirrors
Recap:
Diffuse reflection: gives a blurry image (or none
at all)
Specular reflection: gives a clear image
Mirror types:
PLANE
CONVEX
CONCAVE
Plane Mirrors
• The image formed by plane
mirrors can only be seen
behind the mirror.
• This is known as a virtual
image.
• Image is the same size as the
object.
• Only the right and left of the
image is changed.
Curved Mirrors
• Curved mirrors can be either
– concave (making a little cave) – Causes light to converge
– convex (vexing out in the middle) – Causes light to
diverge
Law of Reflection
Ray Diagrams
• Show path of light from object  mirror 
away from mirror
• Allows you to determine the location and
properties of an image formed by a mirror or
lens
Ray Diagram: Basic set-up
mirror
r
(radius of
curvature)
f
(focal length)
C
(center of
curvature)
Principal axis
F
(focal point)
** r = 2f
Ray Diagrams: images
• REAL vs. VIRTUAL
• UPRIGHT vs. INVERTED
• SAME SIZE, SMALLER, ENLARGED
COMPARE IMAGE TO ORIGINAL OBJECT
Real or Virtual
Real images can project on a screen
Virtual images can only
be seen in a mirror
Upright or Inverted
Upright images are oriented the same
as the object
Inverted images are oriented in the
opposite direction as the object
Reduced or Enlarged
Reduced images are smaller in size
than the object
Enlarged images are larger in size
than the object
Get ready to draw diagrams…
• Take 2 different colored pencils
• Take a slice of index card/Ruler
– This will be your straight-edge
– PUT YOUR NAME ON IT & KEEP IT
– Decorate it if you want to
• Take a notes packet
• Ready? Let’s do this!
Concave Mirror A
Step 5:
1: draw second
2:
3:
4:
horizontal
reflected
image from
ray
ray
ray
from
principal
from
from
top
point
top
of
axis
object
of
where
to
object
intersection
through
ray
tohits
mirror
focal
mirror
of
reflected
point
through
horizontally
torays
mirror
focalback
point
F
Image is:
REAL
INVERTED
LARGER
FARTHER
Concave Mirror B
Step 6:
1: draw
2:
3:
4:
5:
continue
reflected
second
horizontal
image
both
from
ray
reflected
ray
ray
reflected
from
principal
through
from
focal
rays
top
ray
axis
focal
point,
behind
ofto
object
point
through
mirror
to mirror
as
top of object,
DASHED
intersection
LINES
oftoreflected
mirror rays
F
Image is:
VIRTUAL
UPRIGHT
LARGER
FARTHER
Convex Mirror
Step 6:
1: draw
2:
3:
4:
5:
continue
reflected
angled
horizontal
image
both
from
ray,
reflected
ray
ray
reflected
aimed
principal
from
fromat
focal
rays
top
ray
focal
axis
behind
of
point
to
point,
object
intersection
through
mirror
to
tomirror
mirror
as of
point where
DASHED
reflected
LINES
raysray hit mirror and out
F
Image is:
VIRTUAL
UPRIGHT
SMALLER
CLOSER
• Questions?
• Begin optics packet!