Passivelemente

Passivelemente, or passive elements, are components in electrical circuits that do not generate electrical power. They can store energy temporarily or dissipate it as heat, but they do not provide gain or power amplification. In traditional circuit theory, passive elements do not contain an internal source of energy and must obey the passive sign convention.

Common passive elements include resistors, capacitors, and inductors. Resistors dissipate energy as heat and convert electrical energy into thermal energy, described by V = IR. Capacitors store energy in an electric field, with impedance Z_C = 1/(jωC). Inductors store energy in a magnetic field, with impedance Z_L = jωL. Transformers are often considered passive energy-transfer devices that couple energy between windings via mutual inductance; they do not add energy themselves.

AC behavior: Resistors provide in-phase voltage and current; capacitors lead current by 90 degrees; inductors lag by 90 degrees. Frequency dependence leads to common functions such as RC and LC filters (low-pass, high-pass, band-pass). DC behavior: Capacitors block steady current (open circuit), inductors act as short circuits after transients. Energy aspects: capacitors and inductors store energy; resistors dissipate energy according to P = VI or P = I^2R.

Non-idealities: real components have parasitic elements such as equivalent series resistance (ESR), equivalent series inductance (ESL), and tolerance, affecting performance at high frequencies. Applications include signal filtering, impedance matching, decoupling, timing networks, and energy storage in power electronics. Compared with active elements (transistors, tubes, operational amplifiers), passive elements cannot generate power but are fundamental for controlling voltage, current, and impedance in circuits.