1-45 RESULTANT REACTANCEX = (X_{L}-X_{C}) or X = (X_{C}-X_{L}). X_{L} is usually plotted above the reference line and XCbelow the reference line. Inductance and capacitance have opposite effects on the current in respect to the voltage in a.c. circuits. Below resonance, X_{C} is larger than X_{L}, and the series circuit appears capacitive. Above resonance, X_{L} is larger than X_{C}, and the series circuit appears inductive. At resonance, X_{L} = X_{C}, and the total impedance of the circuit is resistive. A RESONANT CIRCUIT is often called a TANK CIRCUIT. It has the ability to take energy fed from a power source, store the energy alternately in the inductor and capacitor, and produce an output which is a continuous a.c. wave. The number of times this set of events occurs per second is called the resonant frequency of the circuit. The actual frequency at which a tank circuit will oscillate is determined by the formula: IN A SERIES-LC CIRCUITimpedanceisminimumandcurrentismaximum. Voltage is the variable, and voltage across the inductor and capacitor will be equal but of opposite phases at resonance. Above resonance it acts inductively, and below resonance it acts capacitively.