= Determining a lossy parallel coil from its admittance
For series resistance R and <inductance> L in parallel with <capacitance> C, suppose the applied <voltage> <amplitude> V is fixed. The DC current gives $R=V/I_{\rm DC}$. If the high-frequency current is $I\sim\alpha\omega$, then $C=\alpha/V$. At the nonzero zero-phase <frequency>, current <amplitude> $I_r=VRC/L$ determines $L=VRC/I_r$. The condition $R^2<L/C$ must hold. The inferred zero-phase <frequency> is $\sqrt{1/(LC)-R^2/L^2}$; it is not automatically the exact <frequency> of minimum current magnitude.
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