Transcript No Slide Title

Sounds
Close your eyes and listen to these sounds.
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What is sound?
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Sound is a form of energy that can be
heard and travels in waves.
When matter vibrates or moves back and
forth very quickly, a sound is made.
Sound waves can travel through solids,
liquids, or gases.
Example: When a school bell rings,
parts of the bell will vibrate creating
sound.
How does the ear work?
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Sound waves are sent.
The outer ear “catches the sound waves”.
The middle ear takes the sound waves and “vibrates”
the eardrum.
The inner ear sends the messages to the brain.
Middle Ear
Outer Ear
Sound Waves
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Inner Ear
The brain puts it together and hooray! You hear your
favorite song on the radio.
Sound Travels
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Sound travels in waves.
Sound must travel through matter to
be heard.
Remember: Matter can be a solid, a
liquid, or a gas.
A sound is made when things vibrate.
Sound travels by sending vibrations
through matter.
Sound Travels Through Matter
Gases
Most of the sounds
we hear travel
through gases, such
as air.
Sound waves travel
slowly through the
air.
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For example: Sound
from a bell, a horn,
or an alarm clock
travels through the
air.
http://www.youtube
.com/watch?v=Au1N
kDy_dkU
Liquids
Solids
Some sounds that
we hear travel
through water.
Some sounds that
we hear travel
through solids.
Sound waves travel
a faster through
water than through
the air.
Sound waves travel
very fast through
solids.
Sonar is the way to
use sounds to locate
objects under
water.
What animals use
sonar?
For example: When
you hit a drum, it
vibrates, then the
sound travels
through the air, to
your ears.
Sound makes the air vibrate.
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For sound to be heard, sound
vibrations must have air or some other
kind of matter to travel through.
You cannot hear sound in outer space
because there is no air or other
matter to carry sound vibrations.
How do you think astronauts are
able to talk each other in outer
space?
Sound can also be blocked.
THINK:
Why do some people wear ear
coverings?
Sound Waves
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Each Sound wave
has unique pattern
•
Frequency
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Wavelength
•
Amplitude
Sound mediums
• A medium is a material that sound, a form of
energy, need to transfer
• Speed of sound
– Solid : Fast speed
– Liquid : Medium speed
– Gas
: Slow Speed
• Standard Temperature and Pressure = 3.31 x 102 m/s
– Vacuum : No Sound
Frequency
1) High frequency means more
vibrations hitting the ear.
2. Healthy humans can hear
from 20 Hz to 20,000 Hz
.http://www.youtube.com/watch?v=H-iCZElJ8m0
Pitch
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Pitch is the highest or lowest sound
an object makes.
Objects that vibrate slowly, make a
low pitch. Example-drum.
Objects that vibrate quickly, make a
higher pitch. Example-recorder
Amplitude of Sound
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Volume control
Loudness
Strength of the wave ( measured in db “decibels”)
Energy of the wave
a) Threshold of hearing (0 db)
b) Threshold of pain (120 db)
5) Ultrasonic sound has a
frequency greater than 20,000 Hz.
a) Dogs (up to 35,000 Hz)
b) Bats (over 100,000 Hz)
c) Medical diagnosis
6) Infrasonic sound has a
frequency below 20 Hz; they are felt
rather than heard
(earthquakes, heavy machinery).
www.teenbuzz.org
http://www.youtube.com/watch?v=h5
l4Rt4Ol7M
d. The Doppler effect – the
change in pitch due to a moving
wave source.
1) Objects moving toward you
cause a higher pitched sound.
2) Objects moving away cause
sound of lower pitch.
3) Used in radar by police and
meteorologists and in astronomy.
18. The Doppler
Effect is the
apparent change
in the frequency
of a sound caused
by the motion of
either the listener
or the source of
the sound.
Check WS “it works for
bats”
A sound wave is a
longitudinal wave which
travels in all directions
away from the source.
What do you hear?
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Did you hear something? Maybe the sound
you heard was as quiet as your cat licking
her paws. Or maybe it was loud, like a
siren going by.
Sounds are everywhere, and you have two
cool parts on your body that let you hear
them all: your ears!
No matter where we go, sound waves are
all around us.
Cover your ears!
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Some people who work near loud
machines wear ear coverings.
The coverings block some of the sound
vibrations from reaching the ears.
The ear coverings protect your ears
from the noise.
Have you ever covered your ears?
Why?
Audiologist
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An audiologist is a person who tests
people’s hearing.
They use special machines that make
sounds.
They also help people who do not
hear well.
Have you had your hearing tested?
How You Make Sounds
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We use our vocal cords to make
sounds in our throat.
When we speak, our vocal cords
vibrate.
Place your hand on your throat when
you talk, and you can feel the vocal
cords vibrate.
Loudness or Volume
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Volume is the loudness or the softness
of a sound.
Loud sounds use a lot of energy.
Soft sounds use a little energy.
Example: The harder a drum is hit,
the more the drum will vibrate . The
more an object vibrates, the louder
the sound it makes.
Wave Properties of
Light
Essential Question
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How is light manipulated to cause
ABSORPTION
REFLECTION
REFRACTION
And DIFFRACTION?
Reflection
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occurs when a wave strikes an object and
bounces off
occurs with all types of waves
obeys the Law of Reflection – the angle of
incidence is equal to the angle of reflection
Law of Reflection
Refraction
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When a wave enters a new medium at an
angle, one side of the wave changes
speed before the other side, causing the
wave to bend.
Refraction (cont.)
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amount of bending depends on the speed of
light in both materials
 the greater the difference between the
speeds of light in the two media, the more
the light is bent
 if light slows down as it passes into the new
medium, the light is bent towards the normal
(an imaginary line drawn perpendicularly
through the surface of the material)
 if light speeds up as it passes into the new
medium, the light is bent away from the
normal
Refraction (cont.)
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amount of refraction depends on the
wavelength of the light
 red light is bent the least
 violet light is bent the most
 white light can be separated into
colors by refraction in a prism
Diffraction
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bending of light around a barrier or
through an opening
occurs with all types of waves
Diffraction Website
Interference
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caused when light waves overlap each
other
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constructive – interact to build up wave
destructive – interact to reduce wave
occurs in all types of waves
white light can be separated into colors by
diffraction and interference using a
diffraction grating
Polarization
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Ordinary light has waves that vibrate in all
directions
A polarizing filters acts as though it has tiny slits in
one direction
Only some of the light (vibrating in the same way
of the “slit”) can pass through a polarized filter
Best example of a polarized filter is sunglasses
Polarization Website
Reflection Example
Complete the figure to the right to show the
Law of Reflection.
Refraction Example
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Complete the path of a
light ray as it goes
through water, glass,
and back into air
Prisms - ROYGBIV
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Label the colors of the spectrum you
observed. What caused the white light to
separate into colors?
Match the Description to the
behavior.
Behavior
(diffraction, reflection, absorption,
refraction)
Description of Wave Motion
1.
Bounces off the surface at the same
angle it hit with
2.
Travels through material, but at an
altered bent angle
3.
Travels through the material until it
encounters an obstacle or hole, which
it bends around
4.
Cannot travel all the way through the
material