One of the mysteries of the English language finally explained.
Definition of impedance in US English:
impedance
noun
The effective resistance of an electric circuit or component to alternating current, arising from the combined effects of ohmic resistance and reactance.
Impedance is usually expressed as a complex quantity Z = R + jX, where R is resistance, X is reactance, and j is the imaginary square root of −1
See also acoustic impedance- ‘Electric impedance tomography is a new imaging technique that is potentially capable of monitoring those imbalances.’
- ‘The transponder alters the impedance of the tuned circuit in accordance with the coded pattern.’
- ‘As the signal propagates down a path, the voltage magnitude is related to the effective impedance up to the point in the signal's flight.’
- ‘Figure 3 shows the display when the cable is terminated in its characteristic impedance of 50 ohms.’
- ‘It may be expressed as IX, where X, the reactance, is the imaginary part of the impedance.’
- ‘This was because the coupling resistance value had inverse effects on the amount of current arriving and on the impedance of the neurite.’
- ‘This greatly minimizes crosstalk among signals and helps to balance the effective impedance of each line at high frequencies.’
- ‘An impedance matching circuit is provided for each signal-carrying wire pair of the first and second wire pair sets.’
- ‘A high impedance probe for the spectrum analyzer is essential.’
- ‘If the load impedance is not equal to the transmission line impedance, the wattmeter will indicate the amount of reflected power.’
- ‘The instrument must show the true rms value of the voltage across the measuring impedance.’
- ‘Note that impedance and reactance are both given in units of ‘ohms’ just like resistance.’
- ‘The constant impedance is maintained despite changes in temperature and voltage by using two external resistors to hold the impedances for all the I / O pins, which can number hundreds in the larger parts.’
- ‘Each antenna features vertical polarization, with an impedance of 50 ohms.’
- ‘The technique is based on the principle that lean tissue has a higher electrical conductivity and a lower impedance rate than fat.’
- ‘Electrical impedance spectroscopy is a method for studying the structure of organic and inorganic materials.’
- ‘Will the electric impedance tomography technique be improved further?’
- ‘In contrast, the configurations and sizes of the nozzles of the first and the second head members are identical, and their impedances are also the same.’
- ‘When impedance is reached, the energy shuts off and a tone alerts OR staff members that fusion is complete.’
- ‘The passive antenna elements are coupled to selectable impedance components.’
Usage
Impedance is a specialized electrical term (as defined above), while impediment is an everyday term meaning 'a hindrance or obstruction': a low-impedance power supply; interpreting his handwriting was an impediment to getting business done