Any wave is an oscillation. Fluctuation can occur in a liquid, electromagnetic field, or any other medium. In everyday life, every person every day is faced with a particular manifestation of fluctuations. But what is a standing wave?
Imagine a capacious container in which water is poured - it can be a basin, a bucket or a bath. If now a palm is patted on the liquid, then wave-like ridges will run in all directions from the center of impact. By the way, they are called traveling waves. Their characteristic feature is energy transfer. However, by changing the frequency of claps, it is possible to achieve almost complete visible disappearance. There is an impression that the mass of water becomes jelly-like, and the movement occurs only up and down. A standing wave is this displacement. This phenomenon occurs because each wave that leaves the center of the impact reaches the walls of the tank and is reflected back, where it intersects (interferes) with the main waves traveling in the opposite direction. A standing wave appears only if the reflected and straight lines coincide in phase but are different in amplitude. Otherwise, the above interference does not occur, since one of the properties of wave disturbances with different characteristics is the ability to coexist in the same volume of space without distorting each other. It can be argued that a standing wave is the sum of two oncoming traveling, which leads to a drop in their speeds to zero.
Why, in the given example, does the water continue to oscillate in the vertical direction? Very simple! When superimposing waves with the same parameters at certain points in time, the oscillations reach their maximum value, called antinodes, while in others they are completely damped (nodes). By changing the frequency of pops, it is possible to completely extinguish horizontal waves and also to strengthen vertical displacements.
Standing waves are of interest not only to practitioners, but also to theorists. In particular, one of the models of the structure of the Universe says that any material particle is characterized by some specific frequency of vibrations (vibration): the electron oscillates (trembles), the neutrino oscillates, etc. Further, within the framework of the hypothesis, it was suggested that the vibration mentioned is a consequence of the interference of some, as yet not open, disturbances of the medium. In other words, the authors argue that where those amazing waves form a standing wave, matter arises.
No less interesting is the phenomenon of Schumann Resonance. It consists in the fact that under certain conditions (none of the proposed hypotheses has so far been accepted as the only true one), standing electromagnetic waves arise in the space between the earth's surface and the lower boundary of the ionosphere, whose frequencies lie in the low and ultra-low ranges (from 7 to 32 hertz ) If the wave formed in the “surface - ionosphere” gap goes around the planet and falls into resonance (phase coincidence), then it can exist for a long time without attenuation, self-sustaining. Schumann's resonance is of particular interest because the frequency of the waves almost coincides with the natural alpha rhythms of the human brain. For example, not only physicists are engaged in research into this phenomenon in Russia, but also such a large organization as the Institute of the Human Brain.
The brilliant inventor Nikola Tesla drew attention to standing electromagnetic waves . It is believed that he could use this phenomenon of wave interference in some of his devices. Thunderstorms are considered to be one of the sources of their appearance in the atmosphere. Electric discharges excite an electromagnetic field and generate waves.