Glossary: What is Impedance?
Introduction
Impedance is a fundamental concept in electronics and electrical engineering, extending the concept of resistance to circuits operating in alternating current (AC).
⚡ Quick answer: Impedance, denoted as Z, represents the total opposition a circuit offers to the passage of alternating current. It is expressed in Ohms (Ω) and combines pure resistance and reactance (capacitive and inductive effects).
How Impedance Works
Unlike resistance, which uniformly opposes direct current (DC), impedance varies according to the signal frequency. It takes into account the effects of capacitors and inductors. Mathematically, it is represented by a complex number Z = R + jX, where the real part (R) is the resistance and the imaginary part (X) is the reactance. The latter reflects the phase shift between voltage and current, a crucial phenomenon for designing filters and amplifiers.
Key Technical Characteristics
- Symbol: Z
- Unit of measurement: Ohm (Ω)
- Frequency dependence: Its value changes according to the frequency of the injected signal.
- Components: Vector sum of resistance and reactance.
- Phase shift: Induces a time lag between the voltage wave and the current wave.
