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Re: [Phys-l] frequency and wavelength of sound in air



Hey there, thanksnfor the bery quickmrespond from yoi. More
Questioms if you don't
Mind - Why does sound frequency not change when travelling from one medium (eg air) to another (eg water)? Is it because the sound frequency is like the finger print for each wave ? Then why do we hear sound pitch increase when it travels through helium, which is another different medium as compared to air?

Sent from Julie Quah's Iphone


On Apr 5, 2009, at 9:02 AM, curtis osterhoudt <flutzpah@yahoo.com> wrote:

Hi, Julie,

The "normal" speed of sound in water is about 1.48 mm*MHz (1.48 mm/ microsecond; 1480 meters per second), depending on the water temperature, etc. The "normal" speed of sound in air (STP) is about 0.343 mm*MHz (343 meters per second), depending on various things. Of course, there is some frequency dependence (dispersion) on these numbers, and shock waves can be much, much faster.

If you're asking whether the frequency increases when sound enters water from air, the answer is very nearly always "no" (it's a good student exercise to explain why this is). But because the speed is higher in water than in air (usually), the wavelength increases.

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Down with categorical imperative!
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________________________________
From: Julie Quah <juliequah@gmail.com>
To: Phys-l@carnot.physics.buffalo.edu
Sent: Saturday, April 4, 2009 6:56:43 PM
Subject: [Phys-l] frequency and wavelength of sound in air

Just wondering, if the speed of sound in water is higher than that in air,
Which of its, frequency or wavelength, (or both) increases in water?
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_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l