SELF

4

S.B. Karavashkin and O.N. Karavashkina

At the same time we know from general physics that transversal waves can be produced not obligatory by a source of transversal oscillations. For example, in case of EM field, where namely transversal waves are typical, two charges of a dipole varying in antiphase serve as a source, and each of them can generate only a longitudinal field.

Actually, “an electrical dipole, whose charges under an extraneous source action vary in time periodically, can be presented as a system of two metal spheres connected by a conductor having an incorporated extraneous source in its middle… The periodical variation of the dipole charges is equivalent to the alternating current in a connecting conductor... Due to it, the field generated by an electrical dipole with the alternating moment will coincide with a field generated by l-long conductor in which the extraneous current runs… The investigation of such dipole field enables us to solve the problems of the analysis and synthesis of antennas, because they can be considered as the dipole systems” [4, pp. 96- 97].

Thus, in the considered case, the transversal EM wave is, in its essence, a resultant of the superposition of two longitudinal electrical waves produced by the time-varying electrical charges composing the dipole.

The same for transversal acoustic wave in gas medium. Following to the known analogy (see e.g. [5, pp. 207- 211]), to produce this wave, there is no direct necessity, gas medium to be able to carry the shear deformation. Two acoustical membranes radiating in anti-phase are sufficient to be a source generating it, as it is shown in Fig. 1.

Fig.1. General block scheme generating transverse acoustic wave in gas medium

This is corroborated additionally by the known properties of the wave processes in gas medium.

First, both in gas and in liquid, when two or more waves superpose, not the compensation but interference occurs. It evidences that in the propagation direction of each superposing wave the energy is conserved. Consequently, in the model of process shown in Fig. 1, the resulting transverse wave has to be amplitude-attenuating at an unlimited distance from the source, because this model is, moreover, in a complete analogy with the base model of EM waves. We can easy check it, substituting the acoustic radiators in Fig. 1 by the sources of an electrical field.

Second, both in gas and liquid, acoustic waves have a property to lift off the source of a signal and to propagate in the continuum even after the radiation has stopped.

Third, at large distances from the source, the acoustic radiator, the same as an elementary electrical dipole, has a space-attenuation degree 1/r. It evidences that the acoustic wave has its far field.