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See also: impédance



impede +‎ -ance


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impedance (countable and uncountable, plural impedances)

  1. (physics) A measure of the opposition to the flow of an alternating current in a circuit; the aggregation of its resistance, inductive and capacitive reactance. Represented by the symbol Z.
  2. (physics, usually with “mechanical”) a measure of opposition to motion of something subjected to a force.
  3. (physics, usually with “acoustic” or “sound”) the sound pressure divided by the particle velocity and the surface area through which an acoustic wave propagates.
  4. (by analogy, software engineering, usually with “mismatch”) a measure of the opposition caused by differences between two paradigms, especially between object-oriented development and relational databases
    • 1997, Bhavani M. Thuraisingham, Data Management Systems: Evolution and Interoperation (ISBN 0849394937), CRC Press, page 33:
      Some argue that having impedance mismatch is difficult for programming intensive applications.
    • 2002, Jim Melton, Advanced SQL:1999: Understanding Object-Relational and Other Advanced Features (ISBN 1558606777), Morgan Kaufmann, page 353:
      But the impedance mismatch between SQL and Java was no better than between SQL and other languages.
    • 2004, Scott W. Ambler, The Object Primer: Agile Model-Driven Development with UML 2.0 (ISBN 1397805218), Cambridge University Press, page 442:
      Why does a technological impedance mismatch exist?

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