Inductors Defined
An inductor is a passive electrical component that stores energy in its magnetic field. It consists of a coil of wire through which a current can flow, creating a magnetic flux proportional to the current.
Inductors in DC Circuits
In DC circuits, an inductor acts as an energy storage device. Initially opposing changes in current flow, it eventually allows DC to pass through unchanged, behaving like a short circuit after reaching a steady state.
AC Circuit Impedance
In AC circuits, inductors exhibit reactance that impedes current flow. This reactance is frequency-dependent, increasing with higher frequencies, which makes inductors useful for filtering applications in electrical signal processing.
Inductive Reactance
Inductive reactance (X_L) is calculated by X_L = 2πfL, where f is the frequency and L is the inductance. It causes the current to lag the voltage by 90 degrees in a pure inductive AC circuit.
Real-world Inductor Behavior
Real inductors have resistance and parasitic capacitance, causing a phase shift that is not exactly 90 degrees. This can lead to resonant circuits when combined with capacitors, finding use in radio and telecommunications.
Inductors in Filters
Inductors are key in designing filters like low-pass, high-pass, and band-pass filters. They block high-frequency signals while allowing lower frequencies to pass, which is essential in audio and RF applications.
Q Factor
The quality factor, or Q factor, of an inductor measures its efficiency. A higher Q indicates lower energy loss relative to the energy stored. Inductors with high Q are desirable for narrow bandwidth filters and resonant circuits.