Inductor (inductor) is used to provide the inductance of the device, a variety of insulated wire wound coil called inductive. Its main role is resistive AC pass DC, resistance to high-frequency pass low frequency means that the high-frequency signal through the inductance coil will encounter a lot of resistance, difficult to pass, while the resistance presented by the low frequency signal through it small, i.e. the low-frequency signal can be more easily through it. Inductance shunt capacitor coil DC resistance is almost zero.
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