Physics - EMI/AC Question with Solution | TestHub

In an inductive circuit, voltage leads current (P-4). In a capacitive circuit, current leads voltage (Q-5). At resonance, the circuit behaves purely resistively, so voltage and current are in phase (R-3). A power factor of zero implies $\cos \varphi =0$, meaning $\varphi =\pm \pi /2$. This occurs in a purely inductive (S-2) or purely capacitive (S-1) circuit, where $R=0$.