Let an AC voltage source of the form v = Vmsin\(\omega\)t be connected to an LCR circuit consisting of an inductor (L), a capacitor (C) and a resistor (R) in series
The total impedance Z of the circuit is given by

Phasor Diagram
(Phasor diagram consists of voltage phasors for resistor, inductor, and capacitor. Voltage across R is in phase with current, across L leads current by 90°, and across C lags current by 90°)