Chinese name: impedance mbth: impedance property: physical quantity meaning: the sum of resistance and reactance on the vector. Noun explanation, electrical explanation, mechanical explanation, impedance formula, "impedance" in life, impedance matching technology, input impedance, output impedance, the concept of matching, how to match, and related research. Noun explanation electricity explanation impedance is a physical quantity that represents the performance of components or the electrical performance of circuits. The ratio of the voltage peak (or effective value) Um at both ends of the passive circuit in an AC circuit to the current peak (or effective value) Im passing through the circuit is called impedance, which is expressed by z and the unit is ohm (ω). When u is constant, the larger z is, the smaller I is, and the impedance has a limiting effect on the current. In current, the influence of objects on current resistance is called resistance. Except superconductors, all substances in the world have resistance, but the resistance values are different. Substances with low resistance are called good conductors, such as metals; Substances with high resistance are called insulators, such as wood and plastic. There is also a conductor between them called a semiconductor, and a superconductor is a substance whose resistance is equal to zero, but its resistivity is required to be zero at a sufficiently low temperature and a sufficiently weak magnetic field. In direct current and alternating current, resistance can block both currents; As common components, besides resistors, there are capacitors and inductors, which will not hinder AC and DC like resistors. Capacitor is "blocking DC", that is, it has a blocking effect on DC, that is, DC cannot pass, but AC can pass. Moreover, with the increase of capacitance or alternating current, the blocking effect of capacitance on alternating current becomes smaller, which can be understood as "resistance", but it is not the same as resistance. This is a kind of reactance, which is called "impedance" together with the unit of resistance. Of course, to be precise, "impedance" should have three parts, except these two, which are "inductive reactance". Inductance is the resistance of inductance to current. Unlike capacitance, inductance has no hindrance to DC (if carefully studied, it will also hinder communication during a short transient several milliseconds before power saturation). The unit of inductance is the same as that of capacitance and resistance. Mechanics explains that the concepts of impedance, reactance and resistance not only exist in the circuit, but also in the vibration system, the impedance is expressed by z, which is a complex number and a phasor, including magnitude and phase/polarity. It consists of resistance and reaction. Resistance is the consumption of energy, while reaction is the preservation of energy. In vibration system, the resistance produced by mass is mass resistance, and the resistance produced by stiffness is stiffness resistance. The impedance formula z = r+I (ω l–1(ω c)) shows that the load is a complex of three types: resistance, inductance and capacitance, which are collectively called "impedance" after combination. The mathematical formula is: impedance z = r+I (ω l–1/(ω c)). Where r is resistance, ω L is inductive reactance, and 1/( ω C) is capacitive reactance. ( 1)If(ωl– 1/ωc)>； 0, called "inductive load"; (2) On the contrary, if (ω l–1/ω c)