# Quality Factor

- The quality factor defines the sharpness of resonance.

- It is defined as:
- where
*Q*= quality factor- ω
_{0}= resonance frequency [rads^{-1}] - ω
_{1}= is the frequency below resonance for which the average power has dropped to half that at resonance [rads^{-1}] - ω
_{2}= is the frequency above resonance for which the average power has dropped to half that at resonance [rads^{-1}]

- It is an inherent characteristic of an oscillator that influences its stability. Generally speaking, the higher the
*Q*, the more stable the oscillator, since a high*Q*means that an oscillator will stay close to its natural resonance frequency.

**Examples**-
**Oscillator Type****Quality Factor,***Q*Tuning Fork 10 ^{3}Quartz Wristwatch 10 ^{4}Oven Controlled Crystal Oscillator 10 ^{6}Rubidium 10 ^{7}Caesium Beam 10 ^{8}Hydrogen Maser 10 ^{9}Caesium Fountain 10 ^{10}Mercury Ion Optical Standard 10 ^{14}

In a reactive circuit, the quality factor is the ratio of the reactance in ohms divided by the resistance in ohms.

**See also: **Resonance.

**Subjects: ** Electronics Noise & Vibration Physics