There are many resonance phenomena in nature, such as acoustic resonance of musical instruments, orbital resonance between satellites of some wooden planets in the solar system, resonance of basement membrane in animal ears and resonance of circuits. Humans also use or try to avoid resonance in their technology.
Generally speaking, a system (whether mechanical, acoustic or electronic) has multiple resonance frequencies, which are easy to vibrate at these frequencies and difficult to vibrate at other frequencies. We often study the low frequency system frequency.
If the frequency causing vibration is complex (such as shock or broadband vibration), the system will usually "select" its resonant frequency to vibrate at this frequency, in fact, the system will filter out other frequencies.
The oscillation intensity is the square of the amplitude. Physicists generally call this formula Lorentz distribution, which appears in many physical systems related to resonance. It is also a coefficient related to oscillator damping. Generally speaking, a highly damped system has a relatively wide resonant frequency band, which is also called bandwidth.
Extended data:
All vibration must be represented by displacement, and behind it must be the flow of energy. The fundamental reason why resonance is so powerful is that it makes the external force directly act on the molecular and atomic level (or some other specific level), constantly absorbing energy and making it move violently in a small range.
If the external frequency is inconsistent with the natural frequency, then the external force acts on the whole object, but if it is consistent with the natural frequency, the acting object will directly become molecules and atoms, and resonance will destroy the unity between particles, make them confront each other, and lead to the instantaneous collapse of the whole system.
From the macroscopic vibration system of a simple pendulum, if the pace of external force and the natural frequency of the simple pendulum are the same (for example, when the simple pendulum moves to the highest point, it always gives the simple pendulum an oblique downward force), then the simple pendulum will continuously absorb external energy. The external energy will be completely absorbed every time, and the pendulum will not output any energy to the outside world, so the energy of the pendulum itself will increase sharply.
If the rhythm of the external force is inconsistent with that of the pendulum, the energy absorbed last time may be offset by the next external force, and the gravitational potential energy of the pendulum itself will be offset from time to time by the external force, so that the energy of the pendulum itself will always remain at a fluctuating level, the peak value will not be too high, and the energy will be absorbed, lost, absorbed and lost repeatedly.
In short, the power of resonance lies in that the external force acts on the microscopic level (or specific level) of an object in the most accurate way (or rhythm), so that every basic unit of the object at this level (such as pendulum, atom and molecule) continuously absorbs energy like cancer cells, and then violently displaces, and finally causes great damage at this level.
The process of resonance is similar to a strong positive feedback process, which can make the system expand violently in a short time.
References:
Baidu encyclopedia-resonance