Study Guide
Sound – type of wave?
Speed of sound
Pitch/frequency of sound
Intensity/loudness of
sound
Decibel scale
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Study Guide
Harmonics
Resonance
The ear
Wave/Particle Models of
Light
Electromagnetic spectrum
Energy of a photon
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Study Guide
Color/frequency
Intensity of light
Diffuse/specular reflection
Retina/Rods/Cones
How we see color
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Study Guide
Primary and Secondary
Colors
Mirrors and Reflection
Refraction
Lens and Refraction
Eye Glasses
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Study Guide
Mirages
Total Internal Reflection
Dispersion
Prisms and different wave
speeds
Rainbows
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Sound and Light
Sound
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Properties of Sound
Sound wave are longitudinal
waves, in which particles of
air vibrate in the same
direction the wave travels.
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Properties of Sound
Sound waves have
compressions and
rarefractions.
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Properties of Sound
Sound waves may be
produced differently, but in
all cases a vibrating object
sets the medium around it in
motion.
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Speed of Sound
The speed of sound depends on
the medium and temperature.
The speed of sound in a
particular medium depends on
how well the particles can
transmit the compressions and
rarefractions.
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Speed of Sound
Sound waves travel faster in
solids and liquids than through
gases.
However, some solids, such as
rubber; dampen vibrations so
that sound does not travel well.
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Loudness of Sound
Loudness is determined by
intensity
The loudness of a sound
depends partly on the
energy contained in the
sound wave.
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Loudness of Sound
Intensity describes the rate at
which a sound wave transmits
energy though a given area of
the medium. It depends on the
amplitude of the sound wave as
well as the distance from the
source. (watts/m2)
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Loudness of Sound
Relative intensity is found by
comparing the intensity of a
sound with the intensity of the
quietest sound a human can
hear; the threshold of hearing.
It is measured in decibels (dB)
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Decibel Scale
0 dB Threshold of Hearing
120 dB Threshold of Pain
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Pitch
Pitch is determined by
frequency
Higher-pitch = higher frequency
(Shorter Wavelengths)
Lower-pitch = lower frequency
(Longer Wavelenghts)
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Pitch
Humans hear sound waves with
a frequency between 20 Hz and
20,000 Hz
Below 20 Hz is call infrasound
Above 20,000 Hz is called
ultrasound
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Harmonics
Harmonic give every
instrument a unique sound
Harmonic is the fundamental
frequency and a certain
whole-number multiples of
that frequency.
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Harmonics
Every musical instrument has
a characteristic sound quality
resulting from the mixture of
harmonics.
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Resonance
Resonance is a phenomenon
that occurs when two objects
naturally vibrate at the same
frequency
Natural frequency depends on
the shape, size, mass, and
material an object is make of.
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The Ear
Sound waves pass though the ear
canal and strike the eardrum, they
cause the eardrum to vibrate.
These vibrations pass from the
eardrum through the three small
bones of the middle ear (hammer,
anvil, and stirrup).
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The Ear
When the vibrations reach the
stirrup, the stirrup strikes a
membrane at the opening of the
inner ear, sending waves through
the cochlea.
Resonance occurs in the inner ear
(cochlea).
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The Ear
The cochlea contains a long,
flexible membrane called the
basilar membrane. Different parts
of the basilar membrane vibrate at
different natural frequencies.
Small hair-like nerve cell sense
these vibrations and sends a
message to the brain.
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The Ear
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Sound and Light
The
Nature of
Light
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Light Can Be Modeled
As a Wave
Light Diffracts and Interferes
like a wave
Light also reflects and
refracts
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Constructive and
Destructive
Interference
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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
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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.
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Atoms Emit Energy As
Photons
Absorbs
Energy
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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
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Light Has a Dual Nature
Duality
Different characteristics
depending on the situation
Scientists use different
models depending on what
they are studying
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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.
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The Speed of Light
In a
vacuum it is
called ‘c’
Depends on
the medium
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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
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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
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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.
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The Brightness of Light
Depends on the Intensity
Light waves spread out
spherically from the source
Therefore intensity will drop
as distance increases
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Exploring the
Electromagnetic Spectrum
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Radar
System that uses reflected radio
waves
Determine distance, location,
shape and speed
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Sound and Light
12.3
Reflection
and Color
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Light Can Be
Modeled As a Ray
Light ray is a model of light
Represents light traveling
through space in an
imaginary straight line
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When Light Rays Reflect off a
Smooth Surface, They Are
Reflected in the Same Direction.
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When Light Rays Reflect off a
Rough Surface, They Scatter
in Many Different Directions.
Diffuse reflection
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The Law of Reflection
 '
States that when
light rays reflect
off a surface the
angle of
incidence equals
the angle of
reflection.
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The Law of Reflection
Ө = Angle of
Ө’ = Angle of
incidence
reflection
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Normal
The theoretical line
perpendicular to the surface
where light hits a mirror.
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Virtual Image
An image that results from
an apparent path of light rays
Appears behind a mirror
Or in front of a lens
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Flat
Mirror
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Real Image
Light rays really exist at the
point where the image appears.
Appears in front of a mirror.
Or through a lens.
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Concave and Convex
Mirrors
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Concave Mirrors
Can create
real images
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Fun House
Mirrors
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Reflection of Green Light by Leaves
Life Science, Holt Science and Technology, California edition, Holt Rinehart and Winston, San Francisco, 2001
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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
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Colored Filters
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You look at a red tulip,
with green leaves,
under green light. What
would you see?
A black flower with green
leaves
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The Primary Colors of
Light and Pigment
Light
Additive
Pigment
Subtractive
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Primary Colors of
Printing
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Sound and Light
12.4
Refraction, Lenses
and Prisms
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Refraction
Bending of light
rays
From one
medium to
another
Due to changing
speeds
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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.
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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
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Refraction in the
Atmosphere
Creates mirages
Are a virtual image
Heat leads to refraction that
bends the light toward the
sky
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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
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Convex Lens
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Convex Lens
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Convex Lens
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Concave Lens
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diverging lenses
Concave Len.
It bends light outward and
can only create a virtual
image.
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The Eye
the cornea is responsible for the
largest percentage of light refraction
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Camera
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Prism
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Dispersion
The effect in
which white light
separates into
different colors
Due to changes
in wave speed of
the different
colors
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White Light contains all
the colors of the
rainbow
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Rainbows
Caused by
dispersion
And internal
reflection
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An orange looks orange
because it:
reflects orange light and
absorbs other colors.
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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.
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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
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Which structure within eye is
responsible for largest
percentage of refraction of
light?
the cornea
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The unique sound quality of
a clarinet or a violin is
caused by the
relative intensity of different
harmonics in each note.
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A virtual image caused by
reflection of light in the
atmosphere is called:
a mirage.
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White light breaks up into
different colors when it
passes through a prism
because of:
differences in wave speed.
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