The self-induction electromotive force in the inductor coil always counterbalances the change in current in the coil. Inductor coils have an impediment to AC currents, which hinder the size of the inductor, xl, in ohms. Its relationship with the inductance l and AC frequency f is xl=2πfl. The inductor can be mainly divided into high frequency choke coil and low frequency choke coil. Tuning and Selecting Frequency Inductor In parallel with the capacitor, an lc tuner circuit can be formed.