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Salut, J.T.,
What do you mean by the emf and psi abbreviations ?
EMF =3D electromotive force
PSI =3D pounds per square inch ( a unit of pressure ~ 7 kPa)
Mais m=E9fie-toi de ses verts et de ses pas m=FBrs.
If a sound wave in air has an intensity less than, say, 120 dB relative
to 1 pW/m2, the restoring force is proportional to the displacement,
and the speed of the wave is independent of the amplitude. However when
you compress air, the equation of state is PV/T =3D constant. When the
amplitude is comparable to the wavelength, the restoring force
increases much faster than the amplitude. In English it's then called a
shock wave, and travels at a speed faster than the low-amplitude speed
of sound. Yes, close to the lightning stroke you can get a shock wave.
Amiti=E9s,
Zigoteau.
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