Editing Q factor (section)

=== Stored energy definition ===
The other common nearly equivalent definition for {{mvar|Q}} is the ratio of the energy stored in the oscillating resonator to the energy dissipated per cycle by damping processes:<ref name="IEEE">Slyusar V. I. 60 Years of Electrically Small Antennas Theory.//Proceedings of the 6-th International Conference on Antenna Theory and Techniques, 17–21 September 2007, Sevastopol, Ukraine. - Pp. 116 – 118. {{cite web|url=http://slyusar.kiev.ua/ICATT_2007_1.pdf|title=ANTENNA THEORY AND TECHNIQUES|url-status=live|archive-url=https://web.archive.org/web/20170828212548/http://www.slyusar.kiev.ua/ICATT_2007_1.pdf|archive-date=2017-08-28|access-date=2017-09-02}}</ref><ref name=":0">{{Cite book|url=https://books.google.com/books?id=kqjdcIV_CCUC&q=quality+factor|title=Network Analysis|last=U.A.Bakshi|first=A. V. Bakshi|date=2006|publisher=Technical Publications|isbn=9788189411237|pages=228|language=en}}</ref><ref name="Green"/>

<math display="block">Q \mathrel\stackrel{\text{def}}{=} 2\pi \times \frac{\text{energy stored}}{\text{energy dissipated per cycle}} = 2\pi f_\mathrm{r} \times \frac{\text{energy stored}}{\text{power loss}}.</math>

The factor {{math|2''π''}} makes {{mvar|Q}} expressible in simpler terms, involving only the coefficients of the second-order differential equation describing most resonant systems, electrical or mechanical. In electrical systems, the stored energy is the sum of energies stored in lossless [[inductors]] and [[capacitors]]; the lost energy is the sum of the energies dissipated in [[resistors]] per cycle. In mechanical systems, the stored energy is the sum of the [[potential energy|potential]] and [[kinetic energy|kinetic]] energies at some point in time; the lost energy is the work done by an external [[force]], per cycle, to maintain amplitude.

More generally and in the context of reactive component specification (especially inductors), the frequency-dependent definition of {{mvar|Q}} is used:<ref name=IEEE/><ref>{{cite book|title=Electric Circuits|isbn=0-201-17288-7|author=James W. Nilsson|year=1989}}</ref>{{Failed verification|date=February 2015|talk=Q factor definition in the context of individual reactive components}}<ref name=":0" />

<math display="block">Q(\omega) = \omega \times \frac{\text{maximum energy stored}}{\text{power loss}},</math>

where {{mvar|ω}} is the [[angular frequency]] at which the stored energy and power loss are measured. This definition is consistent with its usage in describing circuits with a single reactive element (capacitor or inductor), where it can be shown to be equal to the ratio of [[reactive power]] to [[real power]]. (''See'' [[#Individual reactive components|Individual reactive components]].)