The choke action of Hollow Inductor, the self-induced electromotive force inside the air core inductor coil will always oppose the current change in the coil. Therefore, the air core inductor has a certain hindrance to the alternating current, and the magnitude of the blocking effect is the resistance x1, and the unit is ohm. Then it is related to the inductance l and the alternating current frequency fIt is xl=2πfl.
The second is tuning and frequency selection. The air core inductor and capacitor can be connected in parallel to form an lc tuned 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 are also equal, that is, the electromagnetic energy oscillates back and forth between the inductance and the capacitance quality check, which is the lc loop. Resonance phenomenon.
When the resonance, the inductive reactance and capacitive reactance of the circuit are reversed, the inductive reactance of the total current of the loop is the smallest, and the current is also the largest (referring to the AC signal of f="f0"). The lc resonant circuit has the function of selecting the frequency. The AC signal of a certain frequency f can be selected.