A resistor R, an inductor L and a capacitor C are connected in series to an oscillator of frequency n. If the resonant frequency is nr, then the current lags behind voltage when

The current will lag behind the voltage when reactance of inductance is more than the reactance of condenser.Thus, ωL>1ωC or ω>1LC or n > 12πLC or  n > nr  where nr = resonant frequency