impedancj

Impedancj is likely a misspelling of impedancja, the Polish term for impedance, or impedance in English. In electrical engineering, impedance describes the opposition that a circuit presents to the flow of alternating current. It combines resistance and reactance and is a complex quantity, with both a magnitude and a phase.

In AC circuits, impedance is denoted Z and can be written as Z = R + jX, where R is the resistance and X is the reactive part. The reactive component X comprises inductive reactance X_L = ωL and capacitive reactance X_C = -1/(ωC). The unit is the ohm, the same as resistance. The magnitude is |Z| = sqrt(R^2 + X^2) and the phase angle is φ = arctan(X/R). Impedance generally varies with frequency, since X_L and X_C depend on ω.

Impedance combines across components in series and parallel using complex arithmetic. For series circuits, Z_total = Z1 + Z2 + …; for parallel circuits, 1/Z_total = 1/Z1 + 1/Z2 + …. This allows calculation of the overall opposition to AC signals and the distribution of voltage and current among components.

Applications of impedance include impedance matching to maximize power transfer, particularly in radio frequency design where the load is matched to a source or transmission line. Transmission lines have a characteristic impedance (often 50 ohms) that influences reflections and standing waves. Impedance spectroscopy and impedance measurements with LCR meters or impedance analyzers are common methods to characterize materials, components, and circuits across frequencies.