Quality Factor

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Quality Factor

</dt>
A measure of the sharpness of resonance or frequency selectivity of a resonant vibratory system having a single degree of freedom, either mechanical or electrical. See vibration. </dd>
In a mechanical system, this quantity is very nearly equal to one-half the reciprocal of the damping ratio. When used with reference to a lightly damped system, it is also approximately equal to the following: (1) transmissibility at resonance; (2) π/δ where δ is the logarithmic decrement; (3) 2πW/ΔW where W is the stored energy and ΔW the energy dissipation per cycle; and (4) fr/Δf where fr is the resonance frequency and Δf is the bandwidth between the half-power points. Historically the letter Q was an arbitrarily chosen symbol to designate the ratio of reactance to resistance of a circuit element. The name quality factor was introduced later. </dd>

References

This article is based on NASA's Dictionary of Technical Terms for Aerospace Use