Understanding tank circuit resonance
A tank circuit stores electrical energy by exchanging it between an inductor and a capacitor. The capacitor stores energy in its electric field. The inductor stores energy in its magnetic field. When connected together, the two components can oscillate at a natural frequency. This natural frequency is called the resonant frequency. Its ideal value depends only on inductance and capacitance.
Why resonance matters
Resonance is useful whenever a circuit must select, generate, or reject a narrow frequency range. Radio receivers use tuned circuits to select stations. Oscillators use resonant networks to establish predictable operating frequencies. Filters use resonance to shape signal response. Wireless power systems can also use resonant behavior for efficient energy transfer. Small changes in component values shift the resonant frequency, so tolerances matter.
LC and RLC behavior
An ideal LC circuit has no resistance and therefore has no energy loss. Real circuits always contain resistance from winding wire, connections, dielectric losses, and other components. Adding resistance creates an RLC circuit. Resistance lowers the quality factor and broadens the frequency response. A higher Q generally means a narrower bandwidth and stronger selectivity. Series and parallel RLC circuits use different Q formulas because resistance affects them differently.
Practical interpretation
This calculator converts all selected units to SI units before calculating. It also compares inductive and capacitive reactance at resonance. Their magnitudes should match closely. Optional resistance enables Q, bandwidth, damping, and half-power calculations. Optional peak voltage and current estimate stored capacitor and inductor energy. These values are idealized and assume lumped components. At high frequencies, parasitic capacitance, parasitic inductance, skin effect, and component self-resonance can noticeably shift measured results. Use manufacturer data when precision matters. For bench testing, compare calculated resonance with oscilloscope or network analyzer measurements. Record component tolerances and temperature because both can influence frequency stability.