Impedance is an electrical quantity that describes the total resistance of an electrical circuit to the current passing through it. Impedance includes resistance (resistance) and reactance (resistance to change in current) and is a fundamental concept in electrical circuit theory and electrical engineering.
The definition of impedance is as follows:
The impedance (denoted by the letter "Z") of an electrical circuit is measured in ohms (Ω) and is a complex quantity, meaning that it has a real part (resistance) and an imaginary part (reactance). Resistance (R) measures the resistance to current in a circuit, while reactance (X) measures the resistance to change in current, which can be caused by inductance or capacitance in the circuit.
Impedance is often used in the analysis and design of electrical circuits, especially when dealing with complex signals such as signals in the frequency domain, such as in circuit analysis in radio electronics or transfer function calculations in electronic design.
For a resistor that has only resistance and no reactance, the impedance is the same as the resistance and is measured in ohms. For an inductor or capacitor that has a reactance, the impedance is a complex value and depends on the frequency of the current passing through the circuit. Impedance is an important concept in a wide range of applications, including electronics, electrical engineering, radio electronics, and analog systems.