This appendix is added for those readers who might need it for other application than electric circuits, such as in communications. For parallel and series circuits a quality factor Q can be defined using the values of the three components. Q is a ratio; so it is a number without any unit. Here R is the resistance of a resistor that is part of the RLC and must not be confused with the internal resistance of a coil as an inductor.

For a parallel RLC circuit the quality is

$$Q=R\sqrt{\frac{C}{L}}$$ | (F.1) |

At the resonance frequency, for which X_{C} = X_{L}, C can be substituted in terms of L and Equation F.1 assumes the form

$$Q=\frac{R}{{X}_{L}}$$ | (F.2) |

Because X_{C} = X_{L}, Q can also be written as Q =

For a series RLC the quality is X_{C}

$$Q=\frac{1}{R}\sqrt{\frac{L}{C}}$$ | (F.3) ... |

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