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Electrical & Electronics Engineering vocabulary · Voltage, Current and Power

Impedance

Meaning in electrical & electronics engineering, with examples

/ɪmˈpidəns/nounCommon term

In electrical & electronics engineering, impedance means: The total opposition a circuit offers to alternating current, combining resistance and reactance. It is measured in ohms and usually changes with frequency.

In Turkish: empedans

How it is used

Used in AC circuits, audio, RF and signal integrity. Engineers talk about input and output impedance, the characteristic impedance of a cable or trace (often 50 Ω, or 90–100 Ω for differential pairs), impedance matching and high-impedance inputs.

Example sentences

  1. The USB data lines need a controlled impedance of 90 Ω differential.

  2. The oscilloscope input has an impedance of 1 MΩ.

Common collocations

  • input impedance
  • output impedance
  • characteristic impedance
  • impedance matching
  • controlled impedance
  • resistanceHow strongly a material or component opposes the flow of electric current. It is measured in ohms (Ω); for the same voltage, higher resistance means less current.
  • capacitanceThe ability of a component or structure to store electric charge, measured in farads (F). Practical values are usually in microfarads (µF), nanofarads (nF) or picofarads (pF).
  • inductanceThe property of a coil or conductor that opposes changes in the current through it by storing energy in a magnetic field. It is measured in henries (H), often in µH or mH.
  • traceA copper line on a PCB that carries current or a signal between pads, working like a flat wire. British engineers often call it a track.
  • frequencyThe number of times a signal repeats its cycle in one second, measured in hertz (Hz). Mains electricity in Turkey has a frequency of 50 Hz.

More terms: Voltage, Current and Power

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