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Name: Margaret T.
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 5/24/2004


Question:
Are energy and frequency related? What I mean by this is can a wave have a high frequency and low energy and if so what does this mean? Does this mean that since I know that energy and amplitude are proportional and amplitude and loudness are proportional that a wave can reach me quickly but be very quite or visa- versa?


Replies:
This is a tricky question because it depends upon what kind of wave you mean. The energy of a "classical" sound wave is proportional to the square of the amplitude, i.e.: E = |A|^2. But at the atomic level that no longer applies and E = h*f where f is the frequency and h is Planck's constant, but that is electromagnetic waves at the quantum level. Now back to sound waves. "Loudness" is different. Loudness is our ear's (and brain's) response to a sound wave. This does depend on the amplitude of the wave, but it also depends upon the frequency. And if the sound is not a single frequency, the "loudness" depends upon the distribution of overtones of the fundamental (the 'pitch'). All of this "goes out the window" if you now mean a sonic boom, because now the "wave" is traveling faster than the speed of sound and the same physics does not apply. So the "answer" to your question has a lot of "ifs" attached.

Vince Calder



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