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A wave is a physical quantity or a disturbance of a physical quantity that propagates in a specific form in space.

It is an important form of material movement and widely exists in nature.The transmitted physical quantity disturbance or vibration has many forms, the transmission of mechanical vibration constitutes mechanical wave, the transmission of electromagnetic field vibration constitutes electromagnetic wave, the transmission of temperature change constitutes temperature wave, the transmission of crystal lattice vibration constitutes lattice wave, and the transmission of spin magnetic moment When the disturbance propagates in the ferromagnet, a spin wave is formed, and any disturbance of a macroscopic or microscopic physical quantity can form a wave when it is transmitted in space.

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The most common mechanical wave is the propagation process of the mechanical motion of the particles constituting the medium in space, such as waves in strings, water waves, sound waves in air or solids, etc.The premise of these waves is that there is an elastic force or quasi-elastic force interaction between adjacent particles of the medium. It is by means of this interaction force that the vibration of a certain point is transmitted to adjacent particles, so these waves are also called elastic waves. .

Waves can be classified according to the relationship between the vibration direction and the propagation direction. The vibration direction is consistent with the wave propagation direction, which is called longitudinal wave, and the vertical wave is called transverse wave.It can also be divided into two types according to the nature, namely mechanical waves and electromagnetic waves.Mechanical waves are the transfer of momentum and energy in matter caused by the propagation of disturbances.For example, waves propagating along strings or springs, sound waves, water waves.We call the matter that propagates the wave as the medium, which is deformable or elastic and continuous.For electromagnetic waves or gravitational waves, the medium is not necessary, and the disturbance that propagates is not the movement of the medium but the field.

It can be said that waves are ubiquitous in nature.

There are constant fluctuations in the solid.From the perspective of large objects, such as earthquake waves often appear on the earth; from the perspective of small objects, such as the lattice waves that are constantly transmitted between the atomic lattices of crystals.

The most common light in our lives is a kind of electromagnetic wave.It can propagate not only in fluids, solids and plasmas, but also in a vacuum.The universe is filled with all kinds of light and all kinds of radio.General relativity also predicts the existence of gravitational waves.A stronger source of gravitational waves is thought to be a binary star system.Particles with mass also have the nature of waves, so there are so-called matter waves, such as electron waves and neutron waves (see wave-particle duality).Waves are an extremely widespread phenomenon in the universe.

Waves have some unique properties that, from the point of view of classical physics, are distinct from particles.These properties mainly include wave superposition, interference phenomenon, diffraction phenomenon and so on.

First of all, superposition is a very important property of waves (specifically, linear waves, see below).If two or more columns of the same wave meet in space, in the coexistence space, the total wave is the vector sum of each component wave (that is, not only the amplitude but also the phase are considered when adding), and each component wave does not affect each other , and still maintain their respective properties after separation.

The interference phenomenon is due to superposition. When two columns of the same type of waves with the same frequency and fixed phase difference coexist in space, the amplitudes will be mutually strengthened or mutually weakened.When they strengthen each other, they are called constructive interference, and when they weaken each other, they are called destructive interference.

The diffraction phenomenon is that when a wave encounters a large obstacle or a hole in a large obstacle during propagation, it will bypass the edge of the obstacle or the edge of the hole, showing a curved path, and spread out behind the edge of the obstacle or the hole. derived phenomenon.The larger the wavelength relative to the obstacle or aperture, the stronger the diffraction effect.Diffraction is an important example of wave superposition.The wavefront near the edge is decomposed into many point wave sources, each of which emits wavelets, and these wavelets are superimposed on each other, resulting in a diffraction pattern in the geometric shadow area of ​​the obstacle.

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I have no intention of studying and can't help coding... I may become a □□ writer who is elusive =_=

Two paragraphs of strange characters are added in front of each other, which is the external link of the picture. If it succeeds, it will basically be in this form when it is locked in the future.Originally, I was pinched so many times by the pliers of the river crab, and wanted to change to a castrated version, but I was not reconciled, so it was a little hard to watch... sorry.

Forgive me, forgive me——2017.10.1422 52:33:[-]

It's cold, I found that the picture was hung, and moved the content to the previous chapter, it seems to be ok. ——17.12.27

I failed... I'm fucking mad, it's really hard to drive a car, the strange characters in the middle are preceded by ,,,,, extraction code lfcq——17.12.28