Driven RLC branch with a parallel shunt resistor ($U_{\max }/W_{\mathrm{diss}}={\omega }_{0}L/(4\pi R)$)

An ideal sinusoidal voltage source drives a series $R,L,C$ branch and a separate resistor $R$ in parallel. At the series resonance, the reactive stored energy is $L{V}_0^2/(2R^2)$, while both resistors together dissipate $2\pi V_0^2/({\omega }_{0}R)$ per cycle. Counting only the series resistor overestimates the stored-energy-to-dissipation ratio by a factor of two.