• summary_type: application
• word_count: 150

In parallel AC circuits, voltage is common and currents add as phasors. For parallel LCR: total current I = sqrt(I_R^2 + (I_L - I_C)^2), where I_R = V/R, I_L = V/X_L, I_C = V/X_C. The admittance Y = 1/Z. At resonance in a parallel LC circuit (anti-resonance): I_L = I_C, total current is minimum (ideally zero for pure L and C), and impedance is maximum. This is the opposite of series resonance (where Z is minimum). Resonant frequency: same formula omega_0 = 1/sqrt(LC). A parallel LC circuit at resonance acts as a band-stop filter (rejects the resonant frequency). In practice, the inductor has resistance r: at resonance, Z = L/(Cr) (dynamic impedance), and the circuit draws a small current V*Cr/L. Parallel resonant circuits are used in oscillators and frequency-selective networks.