Can you describe the behavior of an RLC circuit when a square wave input is applied?

Low-frequency regime:

When the frequency of the square wave is significantly lower than the resonant frequency of the RLC circuit, the behavior will resemble that of a DC circuit. At low frequencies, the inductor acts as a short circuit (ideal wire), and the capacitor acts as an open circuit (ideal insulator).

During the positive half-cycle of the square wave, the capacitor charges up through the resistor. The inductor opposes abrupt changes in current and gradually builds up the current.

During the negative half-cycle of the square wave, the capacitor discharges through the resistor, and the inductor again opposes abrupt changes, causing a gradual decrease in current.

The output waveform will show the charging and discharging characteristics of the capacitor with smooth transitions during each square wave half-cycle. The waveform may not follow the input square wave exactly due to the inductive and capacitive effects.

Resonance regime:

When the frequency of the square wave approaches the resonant frequency of the RLC circuit, the behavior changes significantly. At the resonant frequency, the reactances of the inductor and capacitor cancel each other out, resulting in a lower impedance across the RLC circuit.

The current through the circuit will reach its maximum amplitude, causing the output voltage across the components to peak.

The phase shift between the voltage and current will be close to zero.

High-frequency regime:

At high frequencies, the inductive reactance becomes significant, and the capacitor acts as a short circuit. The impedance across the RLC circuit increases due to the inductor's opposition to rapid changes in current.

The output voltage waveform will start to show distortions and filtering effects due to the inductive and capacitive properties of the components.

The output waveform may be heavily attenuated, and the sharp edges of the square wave may become rounded off.

In summary, the RLC circuit's behavior when a square wave is applied will vary depending on the frequency of the square wave. At low frequencies, it will behave like a simple RC circuit with gradual charging and discharging of the capacitor. At the resonant frequency, the current will peak, and at high frequencies, the circuit's behavior will be dominated by inductive and capacitive effects, leading to filtering and attenuation of the square wave.