**Q** : Exchange Rate

**Quadratic Mean** under RMS : Root Mean Square

**Quality Factor** IEC Definition, a measure of sharpness of resonance of a system, being 2π times the ratio of the maximum stored energy to the energy dissipated during one cycle

● Note : 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

**Quality Factor : Q** sharpness of Resonance, another term for Amplification Factor .

**International System of Quantities : ISQ** IEC Definition, system of quantities based on the seven base quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity

● Note 1 : the International System of Quantities is published in the International Standard ISO/IEC 80000, Quantities and units.

● Note 2 : the International System of Units (SI) is based on the ISQ.

See also : Symbols

**Quotient** ratio of two numbers or quantities to be divided, for example a measured Sound Pressure to the Reference Sound Pressure.