V.2 No 1

3

Transversal acoustic wave in gas

E-mail: selftrans@yandex.ru   , selflab@mail.ru

In this paper we will consider the results of the experiment carried out in order to reveal and investigate prematurely the properties of transverse wave in gas medium. We will present the theoretical substantiation that such wave can exist in gas medium, where the property to transmit the transverse deformation is absent. This effect is possible when the sources of longitudinal oscillations oscillate in anti-phase. We will prove theoretically and corroborate experimentally that as a result of this superposition, there forms a wave having all properties of the wave process in free space. The transversal acoustic wave has its near and far fields and typical properties inherent in them. The result of such superposition can be considered as the independent wave process in the far field, since its properties basically differ from the typical properties of the interference that bases, as is known, on the principle of oscillation superposition. A stable signal phase delay is experimentally ascertained in this field, as well as the presence of the polarisation plane and disappearance of the signal inversion typical for the near field and interference.

Keywords: Wave physics; Acoustics; Acoustic waves production and propagation; Technique of transversal acoustic waves production; Polarisation method of the acoustic waves investigation

Classification by MSC 2000: 76-05; 76-99.

Classification by PASC 2001: 43.20.+g; 43.38.+n; 43.58.+z; 43.90.+v; 43.20.Hq; 43.20.Tb.

1. Introduction

It is accepted that “neither in gases nor in liquids the transversal shear deformation necessary for transversal waves is impossible” [1, p. 157]. In other words, “liquids and gases cannot resist elastically to the transversal displacement of particles, but only to the volume variation, i.e. to the compression or rarefaction. So in such substances only longitudinal waves can propagate” [2, p. 114].

This condition establishes the prohibition so strongly that even the possibility of transversal waves production in gases and liquids never was examined experimentally in official way, and such experiments were not described in literature. As Professor Doak prompted to one of the authors, “in 1823 Mr. Wheatstone mentioned the “polarization” of acoustic waves, but that was many years before subsequent physicists realized that acoustic waves in a fluid could be best described by a single scalar acoustic velocity potential. (Wheatstone’s paper appeared in the Annals of Philosophy, 20, August 1823.)” [3].