Download All About SOUND? - Ms. Oakes Science

Unit 7
Waves
Understand the properties of
waves and the wavelike property
of energy in earthquakes, light,
and sound.
6.P.1.1
At the end of this unit, students will:
 Compare the properties of waves to the
wavelike property of energy in
earthquakes, light, and sound.
 Explain the relationship among visible
light, the electromagnetic spectrum, and
sight.
 Explain the relationship among the rate
of vibration, the medium through which
vibrations travel, sound, and hearing.
What are waves?
Energy will cause materials to vibrate.
Waves are created when a source (force)
creates a vibration. These vibrations are
carried as “waves” that spread away from
the source and transfer energy.
Waves transmit energy, not matter.
Nearly all waves travel through matter.
Examples of waves
Sound waves: move at different speeds
in different materials; longitudinal waves.
Light waves: unique in their ability to
travel through a vacuum; transverse
waves.
Seismic waves: vibrations in the earth
that release the (potential energy stored in
rocks (due to their relative positions and
consequent pressure) as a result of
earthquakes.
What is sound?
Sound is a form of energy that results when
vibrating materials (disturbance) produce
waves that move through a medium, or matter
(solid, liquid, gas).
Sound waves can be “heard” when they enter
the ear.
http://goo.gl/YwoRS7
Making Sound Waves
1) An object
makes a sound
by vibrating
2) The vibrations pass
through a medium by making
air molecules vibrate.
3) These vibrations
are picked up by the
ear
Air molecules
True or False?
Sound waves can only travel through 1 medium – air?
Sound Waves
Sound waves are longitudinal and begin
with a back-and-forth vibration.
(example: plucking a guitar)
Characteristics of Longitudinal Waves




Wavelength: distance between two identical points
Amplitude: measurement of height of wave
Compression: particles are squeezed together
Rarefaction: particles are spread apart
Example: a slinky, a spring
*
Characteristics of Sound
 Frequency: measurement of how often the wavelength repeats itself
- measured using Hertz (Hz)
- Pitch (how high or low sound is) depends on frequency
* high frequency = high pitch
 Amplitude: measurement of height of wave
- high amplitude contains more energy so sound
wave with high amplitude is perceived as loud
- measured using decibels (dB)
- loudness depends on amplitude
Loudness Scale
measured in decibels (dB)
Interaction of Sound Waves
Sound waves can:
 reflect off objects; creates echo
 diffract through narrow openings
and around barriers; bend or spread
 interfere with each other.
Doppler Effect
Frequency changes due to the movement of
the sound source
http://goo.gl/1GQdir
Example:
Coming: high pitch, high frequency
Going: low pitch, low frequency
Speed of Sound
Sound travels by particles vibrating.
Through which state does sound travel fastest? Why?
Remember what the particles look
like in a solid, liquid and a gas:
solid
liquid
gas
In which state are the particles closest together?
In which state are the particles farthest apart?
solid
gas
Speed of Sound
Sound travels fastest through solids
because
the particles are closer together than
in a liquid and a gas,
so
the vibrations are more easily passed
from particle to particle.
https://www.nde-ed.org/EducationResources/HighSchool/Sound/speedinmaterials.htm
How fast does sound travel?
Rubber
Air (20°C or 68°F)
Air (40°C or 104°F)
Lead
Water
Gold
Wood
Glass
Aluminum
•
•
•
60 m/s
343 m/s
355 m/s
1,210 m/s
1,500 m/s
3,240 m/s
3,850 m/s
4,540 m/s
6,320 m/s
Sound can travel faster through mediums with higher elastic
properties (like steel) than it can through solids like rubber, which
have lower elastic properties.
Sound travels slower in dense mediums (cooler air).
In gases, sound travels quicker when the medium is warm because
the molecules move faster.
Can sound travel in a vacuum?
 A vacuum is an area without any air, like
space.
 Sound cannot travel through a vacuum
because there is no matter for the vibrations
to work in.
 The sound wave gets smaller and smaller
until it disappears.
http://goo.gl/YANcQA
How The Ear Works
1. Sound waves
are collected
by the pinna
or ear lobe.
1
6. The auditory nerve
takes the signals to
the brain
6
5. The cochlea
4
2
5 turns amplified
3
vibrations into
2. The waves
electrical
travel along
signals.
the ear canal.
4. The hammer, anvil,
and stirrup amplify
3. The waves
make the ear the vibrations.
drum vibrate.
http://studyjams.scholastic.com/studyjams/jams/science/human-body/hearing.htm
Wax build-up
Outer
Ear
Hearing Damage
Flattened Cilia
Perforated ear drum
Middle
Ear
Inner
Ear
Fluid build-up
ear infection
Otosclerosis
What is light?
Light is a form of energy emitted by the Sun
as well as light-producing objects on Earth.
Something can be “seen” when light waves
emitted or reflected by it enter the eye.
How does light travel?
Light travels in a straight line until it hits an object.
When that happens, the light can be absorbed,
reflected, or refracted, depending on the surface it hits.
: light is taken in – not reflected or
transmitted.
: an effect that occurs when light hits a
smooth, shiny surface; light changes direction and a
mirror image is reflected.
: light is bent as it passes from one
substance to another.
https://goo.gl/Bu4pTI
Light Waves
Light travels in transverse waves.
Sound Waves vs. Light Waves
Longitudinal Wave:
Transverse Wave:
amplitude: height of wave
wavelength: distance between 2
identical points
rarefaction: particles spread out
compression: particles compress
amplitude: height of wave
wavelength: distance between 2
identical points
crest: highest point of wave
trough: lowest point of wave
Speed
of
Light
vs.
Speed
of
Sound
Light travels at a constant speed of 299,792,458 meters per second, but the
speed of sound is only 343 meters per second. So, light travels faster than
sound.
However, the human body can hear faster than it can see, taste, smell, or
feel. Because hearing or seeing only starts when a sound or light reaches
your ear or eye, it doesn’t matter how fast the light gets to your eye or the
sound gets to your ear. The only thing that matters is how long it takes to
get from your eye to your brain or your ear to your brain.
Once a sound wave reaches your ear, your brain can recognize it in just
0.05 seconds. That’s ten times faster than the blink of an eye!
Can light travel in a vacuum?
 A vacuum is an area without any air, like
space.
 Light waves can travel through a vacuum
because they do not require a medium.
 The wave does not dissipate (grow smaller)
no matter how far it travels, because the
wave is not interacting with anything else.
http://goo.gl/YANcQA
What is the
Electromagnetic Spectrum?
It is the collective term for all possible
frequencies of electromagnetic radiation.
The spectrum includes the entire range of
radio waves, radiation, visible light, UV
rays, X-rays, and gamma rays.
https://app.discoveryeducation.com/learn/videos/fbb2dca0-da00-438d-9ff2-2e520f77caf3?hasLocalHost=true
https://goo.gl/xcvDAR
The Visible Light Spectrum
The visible light spectrum is the only portion of the
electromagnetic spectrum that is visible to the human
eye.
It is the rainbow of colors produced when white light
is split by a prism. ( ROY G BIV )
The Visible Light Spectrum
Each color of light has a different wavelength.
- Red light has the longest wavelength
- Blue light has the shortest.
As light passes through a prism, each color is bent by
a different amount and goes out at a different angle.
- Red bends the least
- Blue bends the most.
In a rainbow, each droplet of water acts like a prism,
splitting the white light into the spectrum.
https://app.discoveryeducation.com/learn/videos/5f1ae
325-e52f-49f9-b046-f822572f45e3?hasLocalHost=true
What happens when light strikes:
Opaque Materials: reflects or
absorbs all of the light that strikes it.
(You cannot see through an object,
because light cannot pass through.)
Translucent Materials: scatters
light as it passes through. (You can
usually see something behind an
object, but the details are blurred.)
Transparent Materials:
transmits most of the light that
strikes it. (The light passes
through without being scattered.)
Structure of the Human Eye
Contain lightreceptive cells
(rods & cones);
converts light to
electrical signal
Colored part of eye;
controls size of pupil
and how much light
enters
Rods: for night
vision and b&w
Cones: movement,
patterns, color
Black hole in iris;
lets light pass
through
Allows us to see objects
near and far
Transparent bulge
over pupil; protects;
focuses light onto
retina
Concave: helps
nearsightedness
Convex: helps
farsightedness
Transmits electrical
impulses from retina to the
brain; creates blind spot;
brain takes inverted image
and flips it so we can see
*
Optical Illusions
Something that deceives the eye
by appearing to be other than it is.
*
Are you seeing spots?
*
Look at the cross for 10 seconds.
What do you see?
*
Do you see a rabbit or a duck?
*
Can you read?
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Seismic Waves
Seismic waves are the waves of energy caused
by the sudden breaking of rock within the earth
or an explosion.
They are the energy that travels through the
earth and recorded on seismographs.
Three types:
* P Waves (pressure or primary waves)
* S Waves (sheer waves)
* Surface Waves (originate at earth’s surface)
https://app.discoveryeducation.com/learn/videos/023519c5-746d-4139-83cd-2600721dd859/
*
Types of Seismic Waves
P Waves (pressure or primary waves)
travel as a region of compression.
- Travel the fastest
- Can travel through solid, liquid, and gas
- Push / pull motion
- Longitudinal wave
*
Types of Seismic Waves
S Waves (sheer waves)
travel like vibrations in a bowl of Jello.
- Cause rocks to move in a vertical motion.
- Can travel through solids only
*
Types of Seismic Waves
Surface Waves
- Travel the slowest of the three seismic
waves
- Cause Earth’s surface to move up and
down and side to side
- Cause most damage during earthquake