By hvhipot 
Series resonance is the phenomenon in which the voltage on the reactive element rises above the voltage on the circuit terminals at the maximum current in a circuit, and this current is in phase with the input voltage.
Resonance condition:
The serial connection between L and C and the AC generator;
The frequency of the generator should be equal to the natural oscillation frequency of the circuit, and the characteristic resistance should be equal.
The resistance should be less than 2 ρ, as only in this case will the circuit experience free oscillation supported by an external power series resonance.
Impedance circuit:
Because the characteristic resistances are equal. Therefore, during resonance, the circuit is purely active, which means that the input voltage and current at resonance are consistent in phase. Take the maximum current value.
At the maximum current value, the voltages in parts L and C will be large and equal to each other.
Circuit terminal voltage:
The following relationships:
Therefore
The Q factor of a circuit, during series resonance, represents how many times the voltage on the reactive element is greater than the input voltage of the generator supplying power to the circuit. The transmission coefficient of a series oscillating circuit during resonance