According to Wikipedia, the Q factor$Q$ factor is defined as:
$$Q=2\pi\frac{\mathrm{energy \, \, stored}}{\mathrm{energy \, \,dissipated \, \, per \, \, cycle}}$$$$Q=2\pi\frac{\mathrm{energy \, \, stored}}{\mathrm{energy \, \,dissipated \, \, per \, \, cycle}}.$$
Here are my questions:
- Does the energy dissipated per cycle assume that the amplitude is constant from one cycle to the next.
- Is it always calculated at the resonance frequency?
- If the answer to 2 is yes can you explain why for a forced oscillator system with a damping coefficient of $\gamma$ and natural frequency $\omega_o$ the quality factor is $Q=\omega_o/\gamma$ and not some more complicated expression involving the actual resonant frequency (which is not quite $\omega_o$ and is given by $$\omega_r=(\omega_0^2-\frac{\gamma^2}{2})^{\frac{1}{2}}$$ of the system? Is this just an approximation i.e. are we assuming that it resonates at $\omega_o$ but in fact the actual expression is a big more complicated?
Edit: With using the actual value of $\omega_r$ I get: $Q=(\omega_0^2-\frac{\gamma^2}{2})^{\frac{1}{2}}/\gamma$ is this more correct?