Khi may quay vs toc do n vong/p thi co he so cong suat la $\frac{\sqrt{2} }{2}$ suy ra $R=Z_{L1}-Z_{C1} (1) va cong suat luc nay la P_{o}=\frac{U^{2}}{2R}.$
Khi may quay vs toc do 2n vong/p thi $w$ tang 2 lan so vs n vong/p tuc la $U'=2U$ , $Z_{L2}=2Z_{L1} va Z_{C2}=\frac{Z_{C1}}{2}$
Cong suat khi may quay 2n vong la $P=\frac{4U^{2}.R}{R^{2}+(2Z_{L1}-\frac{Z_{C1}}{2})^{2}}=\frac{4}{13}P_{o}=\frac{U^{2}}{2R}$
Khai trien rut gon dk $5R=2Z_{L1}-\frac{Z_{C1}}{2} (2)$
Tu (1) va (2) co $Z_{L1}=3R$ va $Z_{C1}=2R$
Khi may quay toc do n/2 vong/p thi $U"=U/2 ; Z_{L3}=\frac{Z_{L1}}{2}=\frac{3R}{2} va Z_{C3}=2Z_{C1}=4R$
Khi do cong suat la $P_{3}=\frac{\frac{U^{2}}{4}R}{R^{2}+(Z_{L3}-Z_{C3})^{2}}=\frac{U^{2}}{29R}=\frac{2P_{o}}{29}$