For example, the vibration of the horn cone in audio equipment and the vibration of the sound cavity in the resonance box of various stringed instruments all use the "mechanical vibration"; The reception and emission of electromagnetic waves use "electromagnetic vibration"; The laser is generated by "optical vibration"; Medical technology has become very popular "nuclear magnetic resonance" and so on.
Second, briefly introduce the principle of washing fish:
1, phenomenon:
A certain amount of water is injected into the basin, and the copper ears are rubbed back and forth with wet hands. It can be observed that water drops like fountains are ejected from four fish mouths with the hum of washing fish, and the water column is as high as several tens of centimeters.
2, the content of the principle of fish washing:
From the point of view of vibration and fluctuation, it is due to the forced vibration of the copper basin when the hands rub the copper ears back and forth. This vibration propagates on the water surface and is superimposed with the reflected wave reflected by the basin wall to form a two-dimensional standing wave.
Theoretical analysis and experiments show that the waveform of this two-dimensional standing wave is related to boundary conditions such as the size of the basin bottom and the shape of the horn at the mouth of the basin. Fish washing was carried out in the Han Dynasty in China, and a fish mouth was designed at the jet of water column, which shows that the knowledge of vibration and fluctuation in ancient China has been mastered quite well.
According to the records in the scriptures, half a basin of water was poured, and the ears of the basin were rubbed repeatedly with both hands. It wasn't long before there was a * * * vibration. The water in the basin is divided into four water arrows, which are more than two feet high, giving off the sound of ancient divination, which is consistent with the sound of the yellow bell. According to legend, this thing was used as a retreat device in ancient times. Because of the roar of the vibrating waves, many fish were washed away together and spread for dozens of miles, and the enemy soldiers were scared off by the sound. Washing fish reflects the ancient science and technology of making utensils in China, reaching a superb level. Nowadays, antique earthquake basins are all engraved with dragon shapes, so they are also called dragon washing.