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Inductor coil - electromagnetic coil - the principle of inductance - the working principle of the inductor

The inductance is the ratio of the magnetic flux around the inside of the wire when the alternating current is passed through the wire, and the magnetic flux of the wire is the current that produces the flux.
When a direct current is passed through the inductor, only a fixed magnetic field line is present around it, which does not change with time; however, when an alternating current is passed through the coil, its surroundings will appear over time.
Changing magnetic lines of force. According to Faraday's law of electromagnetic induction, magnetic generation, the varying magnetic lines produce an induced potential at both ends of the coil. This induced potential is equivalent to a "new power supply."
When a closed loop is formed, this induced potential generates an induced current. It is known by Lenz's law that the total amount of magnetic lines generated by the induced current is intended to prevent changes in the magnetic lines of force. Magnetic field change
From the change of the external alternating current power supply, the objective coil has the characteristic of preventing the current change in the alternating current circuit from the objective effect. Inductor coils have similar properties to inertia in mechanics,
Electrically named "self-sensing", usually at the moment when the knife switch is turned on or the knife switch is turned on, a spark will occur, which is caused by a high induced potential.
In short, when the inductor coil is connected to the AC power source, the magnetic lines of force inside the coil will change with the alternating current, causing the coil to generate electromagnetic induction. This kind of coil itself
The electromotive force generated by the change of current is called "self-induced electromotive force".
It can be seen that the inductance is only a parameter related to the number of turns of the coil, the size and shape, and the medium. It is a measure of the inertia of the inductor and is independent of the applied current. Inductor
Function 1. Inductive coil choke action: The self-induced electromotive force in the coil of the inductor is always resistant to the current in the coil. The inductance coil has a hindrance to the alternating current, and the size of the obstruction
Inductive reactance XL, the unit is ohm. The relationship between the inductance L and the AC frequency f is XL=2πfL, and the inductor can be mainly divided into a high frequency choke coil and a low frequency choke coil.
The role of the inductor 2.
Tuning and frequency selection: The inductor coil and the capacitor are connected in parallel to form an LC tuning circuit. That is, the natural oscillation frequency f0 of the circuit is equal to the frequency f of the non-AC signal, then the inductive reactance and capacitive reactance of the loop
They are also equal, so the electromagnetic energy oscillates back and forth between the inductor and the capacitor, and the resonance phenomenon of the LC loop. At the time of resonance, the inductive reactance and capacitive reactance of the circuit are reversed, and the total resistance of the loop current is minimal.
The flow rate is the largest (refers to the f="f0" AC signal), and the LC resonant circuit has the function of selecting the frequency, and can select the AC signal of a certain frequency f. The role of the inductor 3. The inductor also has
filter
Signal, filter noise, stabilize current and suppress electromagnetic interference. The role of the inductor 4.
In electronic equipment, it is often seen that there is a magnetic ring as shown in Figure 2. What are the functions of these small things? This magnetic ring and the connecting cable form an inductor (the wires in the cable are wound around the magnetic ring).
Ring inductance coil), which is a commonly used anti-interference component in electronic circuits, high-frequency noise has a good shielding effect, so it is called absorption magnetic ring, usually made of ferrite material, also known as ferrite
Magnetic ring (referred to as magnetic ring). In Fig. 2, the upper part is an integral magnetic ring, which is a magnetic ring with a mounting clip. Magnetic rings have different impedance characteristics at different frequencies. The impedance is small at low frequencies when the signal frequency
After the rise, the impedance of the magnetic ring sharply increases.
As we all know, the higher the signal frequency, the more radiated, and the signal lines are without shielding. These signal lines become good antennas, receiving various clutter in the surrounding environment.
Frequency signals, which are superimposed on the transmitted signals, may even change the useful signals transmitted, seriously interfere with the normal operation of the electronic equipment, and reduce the electromagnetic interference (EM) of the electronic equipment is already
Consider the issue. Under the action of the magnetic ring, even if the normally useful signal passes smoothly, the high frequency disturbing signal can be well suppressed, and the cost is low.

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