What is resonance phenomenon, what is its harm and what can be applied?

When people give this object another vibration from the outside (called vibration force), if the frequency of vibration force is exactly the same as the natural frequency of the object, the amplitude of the object vibration reaches the maximum, which is called "* * * vibration". Any object has its own natural vibration. When an object receives the oscillation frequency of another object, which is exactly the same as the oscillation frequency of this object, it will produce * * * vibration. The great harm of vibration can make buildings such as bridges and houses collapse instantly, even endanger people's hearts and blood vessels rupture. * * * Vibration technology is widely used in almost all scientific and technological fields such as machinery, chemistry, mechanics, electromagnetism, optics and molecules, atomic physics and engineering technology. 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.