The LCR Series Circuit

What changes with all three elements present. A resistor, an inductor and a capacitor connected in one series loop to an AC source share the SAME instantaneous current $I$ at every point in the loop -- exactly as in the LR and CR circuits -- but now THREE separate voltage phasors must be added together: $V_R$ (in phase with $I$), $V_L$ (leading $I$ by $90^\circ$), and $V_C$ (lagging $I$ by $90^\circ$, i.e. pointing in the OPPOSITE direction to $V_L$ along the same perpendicular line).

Why $V_L$ and $V_C$ partially cancel. Because $V_L$ and $V_C$ point in exactly opposite directions on the phasor diagram (both perpendicular to $I$, but one ahead and one behind), they do not simply add in magnitude the way $V_R$ and $V_L$ did in the LR circuit -- instead, they PARTIALLY CANCEL, and only their NET difference, $V_L-V_C$ (or $V_C-V_L$, whichever is larger), survives as the effective perpendicular component that combines with $V_R$. Working out exactly how this net perpendicular phas …