- : concept
- : 170
At resonance, = , giving = 1/sqrt(LC) and = ). The impedance reduces to Z = R (minimum), current reaches maximum I = , and the phase angle is zero (purely resistive). The quality factor Q = *L/R = sqrt determines the sharpness of the resonance peak. Higher Q means narrower bandwidth ( = = ) and greater voltage magnification: = = QV at resonance. These voltages can greatly exceed the source voltage — this is not an error but a real physical phenomenon. The energy oscillates between L (magnetic) and C (electric) with no net dissipation in the reactive elements. Changing R affects the peak height and width but not the resonant frequency. Changing L or C shifts the resonant frequency. Radio tuning uses a variable capacitor to adjust .