Electrical resonance

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Electrical resonance

Electrical resonance occurs in an electric circuit

Electrical network

An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, transmission lines, voltage sources, current sources, and switches....
at a particular resonance frequency
Resonance

In physics, resonance is the tendency of a system to oscillate at maximum amplitude at certain Frequency, known as the system's resonance frequencies ....
when the impedance

Electrical impedance

Electrical impedance, or simply impedance, describes a measure of opposition to a sinusoidal alternating current . Electrical impedance extends the concept of Electrical resistance to AC circuits, describing not only the relative amplitudes of the voltage and Electric current, but also the relative Phase ....
between the input and output of the circuit is at a minimum (or when the transfer function

Transfer function

A transfer function is a mathematical representation, in terms of spatial or temporal frequency, of the relation between the input and output of a system analysis....
is at a maximum). Often this happens when the impedance between the input and output of the circuit is zero and when the transfer function equals one.

Resonance with capacitors and inductors
Resonance of a circuit involving capacitors and inductors occurs because the collapsing magnetic field of the inductor generates an electric current in its windings that charges the capacitor, and then the discharging capacitor provides an electric current that builds the magnetic field in the inductor, and the process is repeated continually.

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Encyclopedia

Electrical resonance occurs in an electric circuit

Electrical network

Electrical impedance

Transfer function

Resonance with capacitors and inductors

Resonance of a circuit involving capacitors and inductors occurs because the collapsing magnetic field of the inductor generates an electric current in its windings that charges the capacitor, and then the discharging capacitor provides an electric current that builds the magnetic field in the inductor, and the process is repeated continually. An analogy is a mechanical pendulum

Pendulum

A pendulum is a weight suspended from a pivot so it can swing freely.When a pendulum is displaced from its resting Mechanical equilibrium, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position....
. In some cases, resonance occurs when the inductive reactance and the capacitive reactance of the circuit are of equal magnitude, causing electrical energy to oscillate between the magnetic field

Magnetic field

A magnetism field is a vector field which can exert a magnetic force on moving electric charges and on magnetic dipoles . When placed in a magnetic field, magnetic dipoles tend to align their axes parallel to the magnetic field....
of the inductor and the electric field

Electric field

In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field ....
of the capacitor.

At resonance, the series impedance

Electrical impedance

Electrical impedance, or simply impedance, describes a measure of opposition to a sinusoidal alternating current . Electrical impedance extends the concept of Electrical resistance to AC circuits, describing not only the relative amplitudes of the voltage and Electric current, but also the relative Phase ....
of the two elements is at a minimum and the parallel impedance is at maximum. Resonance is used for tuning

Tuning

Tuning can refer to:*Musical tuning**Guitar tunings**Piano tuning*Radio tuning: see tuner*Tuning properties of neurons: see neuronal tuning...
and filtering, because it occurs at a particular frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
for given values of inductance

Inductance

Inductance is the property in an electrical circuit where a change in the current flowing through that circuit induces an Electromotive force that opposes the change in current ....
and capacitance

Capacitance

In electromagnetism and electronics, capacitance is the ability of a body to hold an electrical charge.Capacitance is also a measure of the amount of electric charge stored for a given electric potential....
. It can be detrimental to the operation of communications circuits by causing unwanted sustained and transient oscillations that may cause noise

Noise

In common use, the word noise means unwanted sound or noise pollution. In electronics noise can refer to the electronic signal corresponding to acoustic noise or the electronic signal corresponding to the noise commonly seen as 'Noise ' on a degraded television or video image....
, signal distortion

Distortion

A distortion is the alteration of the original shape of an object, image, sound, waveform or other form of information or representation. Distortion is usually unwanted....
, and damage to circuit elements.

Parallel resonance or near-to-resonance circuits can be used to prevent the waste of electrical energy, which would otherwise occur while the inductor built its field or the capacitor charged and discharged. As an example, asynchronous motors waste inductive current while synchronous ones waste capacitive current. The use of the two types in parallel makes the inductor feed the capacitor, and vice versa, maintaining the same resonant current in the circuit, and converting all the current into useful work.

Since the inductive reactance and the capacitive reactance are of equal magnitude, ?L = 1/?C, so:

where ? = 2pf, in which f is the resonance frequency in hertz

Hertz

The hertz is a measure of frequency per unit of time, or the number of list of cycles per second. It is the SI base unit of frequency in the International System of Units , and is used worldwide in both general-purpose and scientific contexts....
, L is the inductance in henries, and C is the capacitance in farad

Farad

The farad is the SI unit of capacitance. The farad is named after the British physicist Michael Faraday....
s when standard SI units are used.

Electrical resonance

Resonance with capacitors and inductors

See also