Resonance in AC circuits occurs when the frequency of an external AC voltage or current matches the natural frequency of the circuit, resulting in a significant increase in current and voltage amplitudes.
Resonance causes the circuit to become more reactive, meaning it can store and release energy more efficiently. This can lead to increased currents and voltages, as well as changes in the phase relationship between voltage and current.
The natural frequency of an AC circuit is determined by the inductance, capacitance, and resistance of the circuit. It is also affected by the physical dimensions and materials of the circuit components.
At resonance, the reactive power in the circuit is at its maximum, while the active power remains constant. This means that more energy is being stored and released in the circuit without any change in the amount of power being dissipated.
Resonance is used in various applications, such as radio and television broadcasting, where it allows for efficient transfer of energy from the transmitter to the antenna. It is also utilized in electronic filters to select specific frequencies and in power factor correction to improve the efficiency of power distribution.