Do $w_{2}=4w_{1}=>Z_{L2}=4Z_{L1}; Z_{C2}=\frac{Z_{C1}}{4}$
Vi khi $w=w_{1}$ va $w=w_{2} $ mach co cung he so cong suat nen:
$Z_{C1}-Z_{L1}=Z_{L2}-Z_{C2}$
$Z_{C1}-Z_{L1}=4Z_{L1}-\frac{Z_{C1}}{4}$
$Z_{C1}=4Z_{L1}$
Tu gia thiet ban dau $L=CR^2=>Z_{L}.Z_{C}=R^2$
Tu do de dang tinh dk $Z_{L1}=\frac{R}{2}; Z_{C1}=2R$
He so cong suat :
$cos\varphi =\frac{R}{\sqrt{R^2+(Z_{L1}-Z_{C1})^2}}=\frac{2}{\sqrt{13}}$