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QOTD. 1: What is a Transverse wave? A longitudinal wave? 2: Which one needs a medium?. ANSWERS TO QOTD… 11/30/2009. 1:TRANSVERSE: vibrates perpendicular to the direction in which the wave travels LONGITUDINAL: vibrates parallel to the direction in which the wave travels 2: BOTH

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slide1

QOTD

1: What is a Transverse wave? A longitudinal wave?

2: Which one needs a medium?

answers to qotd 11 30 2009
ANSWERS TO QOTD… 11/30/2009
  • 1:TRANSVERSE: vibrates perpendicularto the direction in which the wave travels
  • LONGITUDINAL: vibrates parallelto the direction in which the wave travels
  • 2: BOTH
    • Only ELECTROMAGNETIC WAVES do not require a medium!!
light sound and color

Light, SOUND, and color

Chapter 12 Notes

remember
Remember…
  • TYPES OF WAVES
    • Transverse Waves
    • Longitudinal Waves
    • Electromagnetic Waves (or Light Waves)
slide5

Transverse wave, matter vibrates up and down (perpendicular) to the direction in which the wave travels. A transverse wave can carry energy without using matter.

slide6

Compressional (longitudinal or sound) wave particles are displaced back and forth parallel to the direction of the wave; it requires a medium to travel.

hand drawn way

slide7

At a constant speed, if frequency increasesthewavelength decreases, or

when frequencydecreases the wavelength increases. V = F  

Click here to go to interactive website on frequency and wavelength

speed of sound
Speed of Sound
  • The Speed of sound depends on the medium.
    • Sound waves travel faster through liquids and solids than through gases.
    • In a liquid or solid, the particles are much closer together than in a gas, so the vibrations are transferred more rapidly from one particle to the next.
speed of sound1
Speed of Sound
  • Some solids, such as rubber, dampen vibrations so that sound travels very slowly.
    • Materials like rubber can be used for soundproofing.
speed of sound2
Speed of sound…

The speed of sound can be used to estimate distances. Sound travels at 343 m/s at standard temperature and pressure.

Sound travels best in SOLIDS.Sounds can NOT travel at all in space (or in any vacuum)

slide11

Speed of Sound in a Variety of Mediums

Medium Temp (oC) Velocity (m/s)

Gases

air20 343

Liquids

water201482

Solids

lead1960

copper5010

glass5640

steel 5960

5 summary ideas about sound travels
5 Summary ideas about sound travels:

1. Sound travels in a compressional wave.

2. A higher frequency means a higher pitch.

3. Sound travels fastest through solids

4. Soundcannot travel without a medium.

5. Soundcannot travel in space, or any

vacuum.

loudness
LOUDNESS
  • Loudness of a sound depends partly on the energy contained in the sound waves.
  • Energy of mechanical (or a sound) wave is determined by its amplitude.
  • Therefore, the greater the amplitude of the sound wave, the greater the sound.
loudness1
LOUDNESS
  • Loudness also depends on your distance from the source of sound waves.
  • The INTENSITY of a sound describes its loudness at a particular distance from the source of the sound.
intensity
Intensity
  • The relative intensity of sound is found by comparing the intensity of a sound with the intensity of the quietest sound a person can hear, the threshold of hearing.
  • The relative intensity is measured in units called decibels, dB.
  • Extensive exposure to sounds above 120 dB can cause permanent deafness.
intensity1
intensity

Intensity depends on the strength of the compressions. (VOLUME = intensity)

pitch
PITCH
  • The pitch of a sound is determined by the frequency of the wave, which is measured in Hertz.
  • The greater the frequency, the higher the pitch. (Ex. The squeak of a shoe on the floor has a high pitch. The drone of a semi truck is a low pitch)
pitch1
PITCH
  • Wavelength vs. Frequency (Pitch) of SOUNDS:

Squeak = High Pitch = High Frequency = small wavelength.

Growl= low pitch= low frequency =Large Wavelength

human ear and sound
Human Ear and Sound...

The range of human hearing is between 20 Hz and 20,000 Hz. Most humans cannot hear frequencies outside this range.

ultrasonic vs infrasonic
Ultrasonic vs. Infrasonic
  • Ultrasonic sounds have frequencies above20,000 Hz. (used by dolphins and birds)
  • Infrasonic sounds have frequencies below20 Hz. (used by elephants and whales)
echo echo echo o o o o o
Echo..echo..echo..o..o…o…o…o…

Echo - a sound wave that reflects

off a surface. If you direct a loud

sound at a hard surface, the sound will

bounce back to you.

Reduce echos by using soft

surfaces. (curtains, carpet, padded

walls and seats)

slide22

Echolocation is a way that sound is used to measure distances using echoes.Applications of echolocation include: submarine, ultrasound or sonagrams, and radar. Echolocation is used by dolphins, insects, bats and birds.

echo example problems
Echo Example Problems

C. How far is a dolphin from his pod if the speed of his sonar signal travels at 1482 m/s and it takes 20s for the sound to go from him, to the pod and back?

echo example problems1
Echo Example Problems

pod

dolphin

C.How far is a dolphin from his podif the speed of his sonar signal travels at 1482 m/s and it takes 20 s for the sound to gofrom him, to the podand back?

echo example problems2

dolphin

pod

Echo Example Problems

C. How far is a dolphin from his pod if the speed of his sonar signal travels at 1482 m/s and it takes 20 s for the sound to go from him, to the podand back?

given formula sub answer

V = D

T

echo example problems3

dolphin

pod

Echo Example Problems

C. How far is a dolphin from his pod if the speed of his sonar signal travels at 1482 m/s and it takes 5s for the sound to go from him, to the podand back?

given formula sub answer

V= 1482 m/s

D = D

T =20 2=10 s

V = D

T

1482 = D

10

echo example problems4

dolphin

pod

Echo Example Problems

C. How far is a dolphin from his pod if the speed of his sonar signal travels at 1482 m/s and it takes 5 s for the sound to go from him, to the podand back?

given formula sub answer

1482 = D

10

V= 1482 m/s

D = D

T =20  2=10

V = D

T

What next ?

echo example problems5

dolphin

pod

Echo Example Problems

C. How far is a dolphin from his pod if the speed of his sonar signal travels at 1482 m/s and it takes 20s for the sound to go from him, to the podand back?

given formula sub answer

1482 = D

10

V= 1482 m/s

D = D

T =20  2=10

V = D

T

1482 x 10 =

echo example problems6

dolphin

pod

Echo Example Problems

C. How far is a dolphin from his pod if the speed of his sonar signal travels at 1482 m/s and it takes 20s for the sound to go from him, to the podand back?

given formula sub answer

1482 = D

10

V= 1482 m/s

D = D

T =20  2=10

V = D

T

14,820 m

1482 x 10 =

doppler effect review
Doppler Effect (REVIEW)
  • As the listener moves closer to the source of the sound, the waves have an increased frequency, resulting in a higher pitch.
  • As the listener moves farther away from the source of the sound, the frequency is reduced which results in a lower pitch.
harmonics
HARMONICS
  • Harmonics give every instrument a unique sound.
  • If you play the same note on a tuning fork and a clarinet, the two notes will sound different from each other.
    • A clarinet will produce sounds at several different pitches, while a tuning fork produces a pure tone of only one pitch.
harmonics1
harmonics
  • A tuning fork vibrates only at its fundamental frequency.
  • The air column in the clarinet vibrates at its fundamental frequency and at certain whole-number multiples of that frequency called HARMONICS.
resonance
resonance

Resonance is the tendency of an object to vibrate at the same frequency as another vibrating source.Ex. Speakers in a car can get so loud, the car dash vibrates too. Ex. Hit a tuning fork and rest it on a table.

Rest it on a test tube in a rack.

--Instruments use resonance to amyplify sound.

(ex-guitar…pluck a string and it as well as the body will vibrate)

hearing and the ear
Hearing and the ear
  • SOUND WAVES are transmitted as vibrations through the ear. (see fig 12-7)
  • Vibrations pass through 3 regions in ear.
  • OUTER  MIDDLE  INNER

Middle

ear

Inner

ear

Outer

ear

hearing and the ear1
Hearing and the ear

Waves enter the outer ear, and travel through the ear canal until they strike the eardrum

Vibrating air causes the eardrum to vibrate

These vibrations enter the middle ear, containing the 3 smallest bones in the body

The small bones transfer the vibration to the side of the cochlea

The fluid in the spiral of the cochlea vibrates and creates waves that travel up the spiral

Nerves at different locations along the spiral will respond todifferent frequencies

The nerve cells convert the vibrations in the liquid to electric impulses and send them to the brain

The brain interprets the impulses as a sound

15 min break from notes
15 min break from notes…
  • Take 15 minutes to work SILENTLY on the worksheet you picked up when you came into class. You will need to open your book to page 396 in order to complete the assignment.
regions of the ear pg 396
Regions of the EAR (pg 396)
  • Ear Pina (tiny hairs)
  • Hammer
  • Anvil
  • Eardrum
  • Stirrup
  • Ear Canal
  • Vestibular Organs
  • Auditory nerve
  • Cochlea
ultrasound and sonar
Ultrasound and sonar
  • SONAR

Stands for

Sound Navigation and Ranging.

ultrasound and sonar1
ULTRASOUND AND SONAR
  • SONAR
  • Sonar is used for underwater location.
  • A sonar systemdetermines distance by measuring the time it takes for sound waves to be reflected back from a surface.
  • Calculated using the equation:

d = vt

ultrasound and sonar2
Ultrasound and sonar
  • ULTRASOUND
  • Ultrasound imaging used in medicine.
  • The echoes of very high frequency ultrasound waves, are used to produce computerized images called sonograms.
  • Can safely view organs without

surgery and unborn fetuses.

homework
HOMEWORK…
  • PAGE 398 Section 12.1 Review

1-2 and 4-6

And

Complete all ch 12 vocab!