5.R、L、C元件的有功功率和无功功率 PR=UIcosp =UIcos0=UIPR=U2/R 2r=UIsinp=Usin0°=0 P=U1cosp=U1cos90°=0 QL=UIsino =UIsin90 =UI=PX Pc=UIcosp=UIcos(-90)=0 ÷C Qc=UIsing=UIsin (-90)=-UI-PXc5. R、L、C元件的有功功率和无功功率 u i R + - PR =UIcos =UIcos0 =UI=I 2R=U2 /R QR =UIsin =UIsin0 =0 i u L + - PL=UIcos =UIcos90 =0 QL =UIsin =UIsin90 =UI=I2XL i u C + - PC=UIcos =UIcos(-90)=0 QC =UIsin =UIsin (-90)= -UI= － I 2XC