Well If we talk about the quality factor of any circuit, we say that: It is the ratio of natural frequency of any circuit and the band width. Q = ω0 / Δω Somewhere I read : It is the ratio of the P.D. across the capacitor or the inductor with the P.D. across the resistor in any circuit. Q = P.D. across L or C / P.D. across R My confusion is that what does Quality factor actually signifies ?