In an RLC circuit,what criteria could be used to decide whether the system is overdamped or underdamped? Could we compare the maximum energy stored during one cycle to the energy dissipated during one cycle?
Answer
To establish the damping calculate ζ (damping ratio).
\$\zeta = \dfrac{R_{series}}{2}\sqrt{\dfrac{C}{L}} \$
If ζ is <1 then it is underdamped. If ζ=1 it is critically damped etc..
Q (quality factor) is defined as the peak energy stored in the circuit divided by the average energy dissipated in it per cycle at resonance and, Q is \$\dfrac{1}{2\zeta}\$.
You decide what's the best method for you but for me it's easier to use the ζ formula providing you know the values for R, L and C. If you don't know them then there are other methods that involve looking at the step transient response or the frequency response.
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