Sound Needs a Medium

Video

Wave Characteristics

[ HTML5 ]

St. Mary's Physics Online

 

 

This movie is part of the collection: Prelinger Archives

Production Company: ERPI Classroom Films, Inc. Distributed by Encyclopedia Britannica
Audio/Visual: sound, B&W
Creative Commons license: Public Domain

School blocks YouTube? Use link below.

SoundF_WL_Amplitude2.mp4

 

 

 

 

 

What is this speaker component called?

What kinds of waves does it produce?

High or low frequency?

 

 

 

 

 

Woofer, Outputs low frequency waves

 

 

 

 

II. Characteristics of Periodic Waves

 

A. Frequency(f) = #vibrations/sec

 

 

= # Cycles/# sec

 

 

= Hertz (Hz)

Source: Elroy M. Avery School Physics
(New York: Sheldon and Company, 1895) 202

Clipart ETC

 

hertz

Heinrich Hertz was the first to send
and receive radio waves.

 

 

 

 

 


Frequency

 - Determined by

Source
of Wave,

Not Medium

 

Cycle = (single vibration) 

 

 

 

Ex)

How many cycles between the dots?

 

 

 

3 Cycles

 

 

 

 

 

 

 

Ex) 10 cycles pass a fixed point in a wave train in 5 seconds.
What is the frequency of the wave?

 

f = 10 cycles =  2 cycles 
5 seconds 1 sec

 

 

f = 2 Hertz (Hz)

 

 

 

 

Top View of a Wave

[ HTML5 ]
St. Mary's Physics Online

 

 

 

 

 

 

 

Sound Waves
David Kirby - U. of Calif.

 

 

 

 

 

Top view of a periodic wave
(Each line is a crest)

 

 

 

 

 

 

Crest
Physics 2000

 

 

 

 

 

 

Review - Longitudinal or Transverse?

[ Flash ]

 

 

 

Ex) A wave generator operating for
4 seconds
produces the waves drawn below.

Top view of a periodic wave
(Each line is a crest)

 

How many waves are drawn between A and B? (Be careful!!)

What is the frequency of this
periodic wave train?

 

 

8 cycles

 

 

 

f = 8 cycles/4 sec

 

 

 

f = 2 cycles/sec 

 

 

 

Ex) 2 cycles pass a fixed point in a wave train in 10 sec.

What is the frequency ?

 

 

 

f = # Cycles/# sec

 

 

 

f = 2 Cycles/10 sec

 

f = .2 Hz

• Sound, frequency is pitch.

 

Source: Elroy M. Avery School Physics
(New York: Sheldon and Company, 1895) 247

Clipart ETC

 

• Light, frequency is color.

 

 

 

Human Ear:

Frequency Range

 

 20 Hz - 20,000 Hz.

 

 

Did you know dogs are

capable of hearing

higher pitch sounds

than humans? 







 

 

The range of frequencies you
can hear changes with age. 

How old are you?

;

 

How to get rid of teenagers 

 

School blocks YouTube? Download link below.

CBC - Moving Sound Technologies.mov

Ringtones the old folks can't hear

Ear Animation

2006 McGraw-Hill Higher Education


 

megahertz

 

 

 

 

 

Enrichment


How the Ear Works

Producer: Bosse (Karl Kurt)
Sponsor: N/A
Audio/Visual: Sd, B&W
Keywords: Perception: Sound; Animation

Creative Commons license: Public Domain

 

How Sound Works

 

NASAconnect

 

Sound of a bell in a vacuum

| Onsite Version |

UC Irvine Physics and Astronomy Videos

 


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Established 1995
Use any material on this site (w/ attribution)