4.4阻抗与导纳 例 。口+ 己知：R=152,L=0.3mH,C=0.2uF, u=5V2c0sot+60°)，f=3×104Hz uc 求i,ur,uL,uc· i=U/Z=0.149∠-3.4A 0.=iR=.=2.235∠-3.4°V U=8.42>U=5 >ug =2.2352 cos(@t-3.4)V 分电压大于总电压 0 U2=joLi==8.42∠86.4V →4=8.42W2cos(ot+86.4）V U 0c=i1jmC=.=3.95∠-93.4°V -3.4° →4=3.95V2 cos(ot-93.4）V 例. L C R u uL uC i + - + - + - 已知：R=15, L=0.3mH, C=0.2F, 5 2 c o s ( 6 0 ) , 3 1 0 H z . 4 u = t + f =    求 i, uR , uL , uC . 4.4 阻抗与导纳 ( ) o 2.235 3. s V 4 V 2.235 2 co 3.4 R R u IR t U  →  = − − = = =  ( ) 8.42 86.4 . V2 cos 86. V 8 42 4 L U j LI L u t     = = = → = +  ( ) / 3 V .95 93.4 3 2 cos 93.4 V .95 C C U I j t C u     = = = → = − − I U Z/ 0.149 3.4 A = =  − UL=8.42 > U=5 分电压大于总电压 U  UL  UC  I R  U   -3.4°