Physics

Resonance in an $LCR$ circuit happens when the inductive and capacitive reactances cancel each other out, leaving only resistance to oppose the current. At this sweet spot, the impedance is minimized and current is maximized for a given voltage. The key is recognizing that $X_L = X_C$—when these opposing "pushbacks" are equal, they vanish, and the circuit behaves as if only the resistor is there.

Resonance in an $LCR$ circuit happens when the inductive and capacitive reactances cancel each other out, leaving only resistance to oppose the current. At this sweet spot, the impedance is minimized and current is maximized for a given voltage. The key is recognizing that $X_L = X_C$—when these opposing "pushbacks" are equal, they vanish, and the circuit behaves as if only the resistor is there.