Inductor: Difference between revisions
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An inductor is a device that stores energy in a magnetic field. Inductors are short circuits to DC current, but their [[impedance]] rises as AC current passing through them has its frequency increased. Extremely high frequency currents see inductors as open circuits. | An inductor is a device that stores energy in a magnetic field. Inductors are short circuits to DC current, but their [[impedance]] rises as AC current passing through them has its frequency increased. Extremely high frequency currents see inductors as open circuits. | ||
In some ways, inductors behave as the opposite of [[capacitors]]. This property is critically important to the circuit design of [[ | In some ways, inductors behave as the opposite of [[capacitors]]. This property is critically important to the circuit design of [[oscillator]]s. | ||
Fundamentally, inductors consist of a conductor, which is usually wrapped into a coil. Many inductors have an insulator inside the coil that has magnetic properties that raise the inductance. Such materials include [[toroid#Powdered Iron|powdered iron toroids]] and [[toroid#Ferrite|ferrite toroids]]. | Fundamentally, inductors consist of a conductor, which is usually wrapped into a coil. Many inductors have an insulator inside the coil that has magnetic properties that raise the inductance. Such materials include [[toroid#Powdered Iron|powdered iron toroids]] and [[toroid#Ferrite|ferrite toroids]]. | ||
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==Online calculators== | |||
[http://www.mantaro.com/resources/impedance_calculator.htm#wire_inductance Various inductance calculators] | |||
{{electronics}} | {{electronics}} |
Latest revision as of 02:14, 1 October 2009
Related wiki pages: Electronic Theory, Capacitors, Resistors, Impedance
An inductor is a device that stores energy in a magnetic field. Inductors are short circuits to DC current, but their impedance rises as AC current passing through them has its frequency increased. Extremely high frequency currents see inductors as open circuits.
In some ways, inductors behave as the opposite of capacitors. This property is critically important to the circuit design of oscillators.
Fundamentally, inductors consist of a conductor, which is usually wrapped into a coil. Many inductors have an insulator inside the coil that has magnetic properties that raise the inductance. Such materials include powdered iron toroids and ferrite toroids.
Inductance
Inductance (L), measured in henries (H) is the effect which results from the magnetic field around a current-carrying conductor. Current flowing through the conductor creates a magnetic flux proportional to the current. A change in this current creates a change in magnetic flux that, in turn, generates an electromotive force (EMF) that acts to oppose this change in current. Inductance is a measure of the amount of EMF generated for a unit change in current.
Inductive Reactance
The impedance of an inductor is given by the formula
- <math>Z = j \omega L \,</math>
where <math>Z\,</math> is the impedance, <math>\omega\,</math> is <math>2 \pi f\,</math>, and <math>f\,</math> is the frequency. <math>j\,</math> is "operator j" from phasor analysis.
In practical terms this leads to:
<math> X_c = 2 \pi F L </math> where:
- <math> X_c </math> is capacitive reactance
- F is the frequency of operation in Hertz
- L is the inductance in Henries
Inductor formulae
Construction | Formula | Dimensions |
---|---|---|
Cylindrical coil | <math>L=\frac{\mu_0\mu_rN^2A}{l}</math> |
|
Straight wire conductor | <math>L = l\left(\ln\frac{4l}{d}-1\right) \cdot 200 \times 10^{-9}</math> |
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<math>L = 5.08 \cdot l\left(\ln\frac{4l}{d}-1\right)</math> |
| |
Short air-core cylindrical coil | <math>L=\frac{r^2N^2}{9r+10l}</math> |
|
Multilayer air-core coil | <math>L = \frac{0.8r^2N^2}{6r+9l+10d}</math> |
|
Flat spiral air-core coil | <math>L=\frac{r^2N^2}{(2r+2.8d) \times 10^5}</math> |
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<math>L=\frac{r^2N^2}{8r+11d}</math> |
| |
Toroidal core (circular cross-section) | <math>L=\mu_0\mu_r\frac{N^2r^2}{D}</math> |
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Online calculators
Various inductance calculators
Electronic Theory | |
Physical quantities | Current * Gain * Impedance * Power * Q of a circuit * Radiated Power Measurement * Reactance* Resistivity * Resonance * Voltage |
Components | Baluns * Bipolar-Junction Transistors * Capacitors * Diodes * Inductors* Lasers * Microphones * Resistors * Transformers * Wire |
Circuits | Attenuators * Digital Signal Processing (DSP) * Dummy load * Filters * LC filters * Power Supply Design * Rectifier Circuits |
Design | Amplifier Design * Oscillator Design |
Electromagnetic Waves | Relative power (Decibels) * Harmonics * Interference and BPL |