\[\tan \phi=\frac{X_{\text{eff}}}{\text{R}_{\text{eff}}}=\frac{\omega L_{\text{eff}}}{\text{R}_{\text{eff}}}=\frac{\omega\left(\text{L}-\text{CR}^{2}\right)}{\text{R}}=\omega\left(\frac{\text{L}}{\text{R}}-\text{CR}\right)\]
\[\tan \phi=\frac{X_{\text{eff}}}{\text{R}_{\text{eff}}}=\frac{\omega L_{\text{eff}}}{\text{R}_{\text{eff}}}=\frac{\omega\left(\text{L}-\text{CR}^{2}\right)}{\text{R}}=\omega\left(\frac{\text{L}}{\text{R}}-\text{CR}\right)\]
\[\tan \phi=\frac{X_{\text{eff}}}{\text{R}_{\text{eff}}}=\frac{\omega L_{\text{eff}}}{\text{R}_{\text{eff}}}=\frac{\omega\left(\text{L}-\text{CR}^{2}\right)}{\text{R}}=\omega\left(\frac{\text{L}}{\text{R}}-\text{CR}\right)\]