dimpédance

Dimpédance is not a widely standardized term in electrical engineering. In many contexts it is simply a misspelling or a French-language variant of impédance, which is the French word for impedance. When encountered in technical writing, it typically refers to the same concept, with spelling variations not affecting its meaning.

Impedance is the complex quantity that relates an alternating voltage to the resulting current in a linear, time-invariant circuit under sinusoidal steady state. It is denoted Z and expressed as Z = V/I for phasor voltages V and currents I. Impedance combines resistance (the real part, R) and reactance (the imaginary part, X): Z = R + jX. The reactance accounts for energy storage in inductors and capacitors, with X_L = ωL and X_C = -1/(ωC).

Impedances add according to circuit topology: in series, Z_total = Z1 + Z2 + ... ; in parallel, 1/Z_total = 1/Z1 + 1/Z2 + ... . The magnitude |Z| and the phase angle φ = arctan(X/R) describe how much voltage leads or lags the current. The real part governs dissipation, while the imaginary part governs energy storage.

Practical uses include impedance matching for maximum power transfer, analysis of AC networks, and impedance spectroscopy, which measures how Z varies with frequency to infer material or component properties. In transmission-line theory, the characteristic impedance Z0 governs reflections and standing waves and must be matched to the load.

Beyond electronics, impedance concepts extend to acoustics and mechanics, where similar ratios of pressure to velocity or force to velocity define an impedance, enabling cross-domain analysis and design.