Impedanties

Impedanties is the Dutch plural form of impedance, an electrical property describing opposition to alternating current in circuits. Impedance generalizes the concept of resistance to AC signals and can be represented as a complex number Z = R + jX, where R is the real part (resistance) and X is the reactive part (reactance).

The reactive part comes from energy-storing components: inductors and capacitors. For a given angular frequency ω, X_L = ωL and X_C = -1/(ωC). Resistance R is typically treated as frequency independent in ideal components, so Z_R = R, Z_L = jωL, Z_C = -j/(ωC).

Impedances combine differently depending on configuration: in series, Z_total = Z1 + Z2; in parallel, 1/Z_total = 1/Z1 + 1/Z2. In AC analysis, voltages and currents are treated as phasors, with V = IZ and the phase of Z indicating whether the circuit current lags or leads the voltage. The magnitude |Z| = sqrt(R^2 + X^2) and the phase angle φ = arctan(X/R).

At resonance, X_L + X_C = 0, leaving a purely resistive impedance. Impedanties play key roles in impedance matching, filter design, and transmission-line systems, where the goal is to maximize power transfer or control signal behavior over frequency.

Practical measurement of impedance is performed with LCR meters or impedance analyzers, often across a range of frequencies in impedance spectroscopy. The concept also extends to complex impedance in materials, electrochemistry, and RF engineering. See also impedance, phasor, complex impedance, and impedance spectroscopy.