Resonant circuits, also knows as "tuned circuits" or "LC circuits" are electric circuits that consist of an inductor L (coil) and a capacitor C (condenser) connected together in series or parallel. LC circuits are used for radio tuning, impedence matching, mixing of signals, and frequency multiplication in radio transmitters, radio receivers and signal generators.

At resonance, parallel LC circuits give high impedance to the signal of a frequency with which it resonates. Use the calculator below to find the resonant frequency of a paraller LC circuit where L and C are of known values.