Sound and Light
The
Nature of
Light
Sound and Light
1
Constructive and
Destructive
Interference
Sound and Light
2
Light Can Be Modeled
As a Wave
Light Diffracts like a wave
Light also reflects and
refracts
Sound and Light
3
Max Planck and Albert
Einstein
Nobel prize winners in physics
Discovered that light, which
usually travels in waves,
sometimes behaves as if it were
made up of a stream of small
quantities, or quanta, of energy
Sound and Light
4
Photon
Small unit of light energy or
electromagnetic radiation. “Packets”
No mass, bundle of energy.
The energy, E, of a photon is
calculated using the equation E = hu,
Where h is Planck's constant and u
is the frequency of the light.
Sound and Light
5
Atoms Emit Energy As
Photons
Absorbs
Energy
Sound and Light
6
Sometimes Light is
modeled as a Stream of
Particles
Explains why light can travel
through the vacuum of space
Light can knock electrons off
a metal plate
Sound and Light
7
Light Has a Dual Nature
Duality
Different characteristics
depending on the situation
Scientists use different
models depending on what
they are studying
Sound and Light
8
Photon Self-identity Problems
Sound and Light
9
Energy of Light Is
Proportional to Frequency
Light is a form of energy.
The energy, E, of a photon is
E = hu,
Where h is Planck's constant
and u is the frequency of the
light.
Sound and Light
10
The Speed of Light
In a
vacuum it is
called ‘c’
Depends on
the medium
Sound and Light
11
Where
you are: Source of light:
Home Outfield fence
Plate
125m (410ft)
Soccer
goal
Earth
Time to get
there:
½ of a
millionth of
a second
Other goal 100m 1/3 of a
(328ft)
millionth of
a second
Moon 376,280km 1 ¼
233,810 miles
seconds
Sound and Light
12
Where Source of light:
you are:
Time to get
there:
Earth Sun 150,000,000 km 8 1/3
(93,000,000 miles) minutes
Earth Proxima Centauri,
4 1/3 years
the nearest star
41,000,000,000,000
km
Sound and Light
13
The Brightness of Light
Depends on the Intensity
The rate at which light
energy flows through a given
area of space is referred to
as its intensity.
Sound and Light
14
The Brightness of Light
Depends on the Intensity
Light waves spread out
spherically from the source
Therefore intensity will drop
as distance increases
Sound and Light
15
Exploring the
Electromagnetic Spectrum
Sound and Light
16
Radar
System that uses reflected radio
waves
Determine distance, location,
shape and speed
Sound and Light
17
Sound and Light
12.3
Reflection
and Color
Sound and Light
18
Light Can Be
Modeled As a Ray
Light ray is a model of light
Represents light traveling
through space in an
imaginary straight line
Sound and Light
19
When Light Rays Reflect off a
Smooth Surface, They Are
Reflected in the Same Direction.
Sound and Light
20
When Light Rays Reflect off a
Rough Surface, They Scatter
in Many Different Directions.
Diffuse reflection
Sound and Light
21
The Law of Reflection
 '
States that when
light rays reflect
off a surface the
angle of
incidence equals
the angle of
reflection.
Sound and Light
22
The Law of Reflection
Ө = Angle of
Ө’ = Angle of
incidence
reflection
Sound and Light
23
Normal
The theoretical line
perpendicular to the surface
where light hits a mirror.
Sound and Light
24
Virtual Image
An image that results from
an apparent path of light rays
Appears behind a mirror
Or in front of a lens
Sound and Light
25
Flat
Mirror
Sound and Light
26
Real Image
Light rays really exist at the
point where the image appears.
Appears in front of a mirror.
Or through a lens.
Sound and Light
27
Concave and Convex
Mirrors
Sound and Light
28
Concave Mirrors
Can create
real images
Sound and Light
29
Fun House
Mirrors
Sound and Light
30
Reflection of Green Light by Leaves
Life Science, Holt Science and Technology, California edition, Holt Rinehart and Winston, San Francisco, 2001
Sound and Light
31
Seeing Color
Objects have color because
they reflect certain
wavelengths of light
The object absorbs all the
other colors
Your brain interprets each
wavelength as color
Sound and Light
32
Colored Filters
Sound and Light
33
You look at a red tulip,
with green leaves,
under green light. What
would you see?
A black flower with green
leaves
Sound and Light
34
The Primary Colors of
Light and Pigment
Light
Additive
Pigment
Subtractive
Sound and Light
35
Primary Colors of
Printing
Sound and Light
36
What are the True Colors?
Sound and Light
37
Sound and Light
38
Sound and Light
12.4
Refraction, Lenses
and Prisms
Sound and Light
39
Refraction
Bending of light
rays
From one
medium to
another
Due to changing
speeds
Sound and Light
40
When light moves from a
material in which its speed is
higher to a material in which
its speed is lower, it is…
Bent toward the normal.
Sound and Light
41
If a light moves from a
material in which its speed is
lower to one in which its
speed is higher,
The ray is bent away from
the normal
Sound and Light
42
Refraction in the
Atmosphere
Creates mirages
Are a virtual image
Heat leads to diffraction that
bends the light toward the
sky
Sound and Light
43
Total Internal Reflection
Light enters one end of a
fiber optic cable and exits
the other end
Complete reflection
Between two mediums
Angle of incidence exceeds
the critical angle
Sound and Light
44
Convex Lens
Sound and Light
45
Convex Lens
Sound and Light
46
Convex Lens
Sound and Light
47
Concave Lens
Sound and Light
48
diverging lenses
Concave Len.
It bends light outward and
can only create a virtual
image.
Sound and Light
49
The Eye
the cornea is responsible for the
largest percentage of light refraction
Sound and Light
50
Camera
Sound and Light
51
Prism
Sound and Light
52
Dispersion
The effect in
which white light
separates into
different colors
Due to changes
in wave speed of
the different
colors
Sound and Light
53
White Light contains all
the colors of the
rainbow
Sound and Light
54
Rainbows
Caused by
dispersion
And internal
reflection
Sound and Light
55
Sound and Light
56
Study Guide
Pitch of a sound
Cornea
Harmonics, Amplitude
Law of reflection
Real image, virtual image
Diverging lens
Electromagnetic spectrum
Sound and Light
57
Intensity, sound and light
Resonance
particle and wave models of light
energy of a photon
Diffuse reflection
Color, frequency
Refraction, normal
total internal reflection.
Prism and differences in wave speed
Sound and Light
58
6. An orange looks orange
because it
a. reflects orange light and
absorbs other colors.
Sound and Light
59
7. When light moves from a
material in which its speed is
higher to a material in which its
speed is lower, it is
a. bent toward the normal.
28. If a light moves from a
material in which its speed is
lower to one in which its speed
Sound and Light
60
9. Which structure within
eye?
b. the cornea is responsible
for the largest percentage of
refraction of light
Sound and Light
61
12. The unique sound quality
of a clarinet or a violin is
caused by the
c. relative intensity of
different harmonics in each
note.
Sound and Light
62
18. A virtual image caused
by reflection of light in the
atmosphere is called
d. a mirage.
Sound and Light
63
10. White light breaks up into
different colors when it
passes through a prism
because of
a. differences in wave speed.
Sound and Light
64
Sound and Light
65