coil in all directions. When a length of wire is formed onto a coil, it coil, the total resistance may be significant . The relationship between inductive reactance. Answer to What is the relationship between inductor Q anda. Winding resistance ?b. Operating frequency?. An inductor usually consists of a coil of conducting material, typically the winding resistance Rw, and it appears in series with the inductance of the inductor. is applied across it then the current would increase according to the equation V.
In this configuration, the inductor decouples DC current, while allowing AC current to pass. Inductors are used extensively in analog circuits and signal processing. Applications range from the use of large inductors in power supplies, which in conjunction with filter capacitors remove ripple which is a multiple of the mains frequency or the switching frequency for switched-mode power supplies from the direct current output, to the small inductance of the ferrite bead or torus installed around a cable to prevent radio frequency interference from being transmitted down the wire.
Inductors are used as the energy storage device in many switched-mode power supplies to produce DC current. The inductor supplies energy to the circuit to keep current flowing during the "off" switching periods and enables topographies where the output voltage is higher than the input voltage.
A tuned circuitconsisting of an inductor connected to a capacitoracts as a resonator for oscillating current. Tuned circuits are widely used in radio frequency equipment such as radio transmitters and receivers, as narrow bandpass filters to select a single frequency from a composite signal, and in electronic oscillators to generate sinusoidal signals.
Two or more inductors in proximity that have coupled magnetic flux mutual inductance form a transformerwhich is a fundamental component of every electric utility power grid.
The efficiency of a transformer may decrease as the frequency increases due to eddy currents in the core material and skin effect on the windings. The size of the core can be decreased at higher frequencies. For this reason, aircraft use hertz alternating current rather than the usual 50 or 60 hertz, allowing a great saving in weight from the use of smaller transformers.
Inductors are also employed in electrical transmission systems, where they are used to limit switching currents and fault currents. In this field, they are more commonly referred to as reactors. Inductors have parasitic effects which cause them to depart from ideal behavior. They create and suffer from electromagnetic interference EMI.
Their physical size prevents them from being integrated on semiconductor chips. So the use of inductors is declining in modern electronic devices, particularly compact portable devices.
Real inductors are increasingly being replaced by active circuits such as the gyrator which can synthesize inductance using capacitors. A ferrite "bead" chokeconsisting of an encircling ferrite cylinder, suppresses electronic noise in a computer power cord.
Large 50 Mvar three-phase iron-core loading inductor at an Austrian utility substation An inductor usually consists of a coil of conducting material, typically insulated copper wirewrapped around a core either of plastic to create an air-core inductor or of a ferromagnetic or ferrimagnetic material; the latter is called an "iron core" inductor.
Since power inductors require high induction levels, high permeability and low saturation points in the core materials are not ideal.
Low frequency inductors are constructed like transformers, with cores of electrical steel laminated to prevent eddy currents. Inductors come in many shapes. Some inductors have an adjustable core, which enables changing of the inductance. Inductors used to block very high frequencies are sometimes made by stringing a ferrite bead on a wire.
Inductor - Wikipedia
Small inductors can be etched directly onto a printed circuit board by laying out the trace in a spiral pattern. Some such planar inductors use a planar core. Small value inductors can also be built on integrated circuits using the same processes that are used to make transistors. Aluminium interconnect is typically used, laid out in a spiral coil pattern. However, the small dimensions limit the inductance, and it is far more common to use a circuit called a gyrator that uses a capacitor and active components to behave similarly to an inductor.
Regardless of the design, because of the low inductances and low power dissipation on-die inductors allow, they're currently only commercially used for high frequency RF circuits.
Shielded inductors[ edit ] Inductors used in power regulation systems, lighting, and other systems that require low-noise operating conditions, are often partially or fully shielded. Air-core inductor[ edit ] An antenna tuning coil at an AM radio station. It illustrates high power high Q construction: The term air core coil describes an inductor that does not use a magnetic core made of a ferromagnetic material.
The term refers to coils wound on plastic, ceramic, or other nonmagnetic forms, as well as those that have only air inside the windings.
Factors Affecting Inductance
Air core coils have lower inductance than ferromagnetic core coils, but are often used at high frequencies because they are free from energy losses called core losses that occur in ferromagnetic cores, which increase with frequency.
A side effect that can occur in air core coils in which the winding is not rigidly supported on a form is 'microphony': Radio-frequency inductor[ edit ] Collection of RF inductors, showing techniques to reduce losses.
The three top left and the ferrite loopstick or rod antenna,     bottom, have basket windings. At high frequenciesparticularly radio frequencies RFinductors have higher resistance and other losses.Resistor, Inductor and Capacitor in Series - Physics4Students
In addition to causing power loss, in resonant circuits this can reduce the Q factor of the circuit, broadening the bandwidth. In RF inductors, which are mostly air core types, specialized construction techniques are used to minimize these losses. The losses are due to these effects: All other factors being equal, greater coil area as measured looking lengthwise through the coil, at the cross-section of the core results in greater inductance; less coil area results in less inductance. Greater coil area presents less opposition to the formation of magnetic field flux, for a given amount of field force amp-turns.
A longer path for the magnetic field flux to take results in more opposition to the formation of that flux for any given amount of field force amp-turns. All other factors being equal, the greater the magnetic permeability of the core which the coil is wrapped around, the greater the inductance; the less the permeability of the core, the less the inductance.
A core material with greater magnetic permeability results in greater magnetic field flux for any given amount of field force amp-turns.
An approximation of inductance for any coil of wire can be found with this formula: It must be understood that this formula yields approximate figures only.
If the hysteresis of the core material is significant, this will also have strange effects on the inductance of the coil. If an inductor is designed so that any one of these factors may be varied at will, its inductance will correspondingly vary. Variable inductors are usually made by providing a way to vary the number of wire turns in use at any given time, or by varying the core material a sliding core that can be moved in and out of the coil.
An example of the former design is shown in this photograph: This unit uses sliding copper contacts to tap into the coil at different points along its length. The unit shown happens to be an air-core inductor used in early radio work.