知识回顾U-RiT=Rzdefi国=joLU=jX,i-joLii1=-j--ixi-joioC/Z-[R+joL-jC
思考问题两阻抗串联，在什么情况下z=z+z,？下列各图中电压有效值U、阻抗模值Z是多少？o8++30V6V3262=Uu8V42V8240V.=52U=10V[z/=14.2U=70V
思考问题成立？两阻抗并联，什么情况下2=Z.Z.下列各图中电压有效值U、阻抗模值Z是多少？4xj42V2Z|= 2.2I=8A1=4-4j=4/2A4+i4知识点测试如图所示电路中，I=（)A.A. 749V.1393C. 5D. 3
3正弦稳态交流电路的计算例题解析R、L、C串联交流电路如图所示，已知R=302、L=127mH、C=40μF，求：电流i及各部分电压UR，uL，Uc;=2202sin(314t+20)VX,=0L=314×127x10=40Q2+11X.==802RMRoC314×40×10-6Z=R+j(X,-X,)=[30+j(40-80))=(30-j40)=50Z-532t1U=220Z20V220/20人+4.4Z73Ai=4.4V2sin(314t+73°)Aucz50Z-53oU220Z20U,=Ri=30×4.4/73=132/73V4.4Z73AZ50Z-53ur=132/2sin(314t+73)VU,=jX,i=j40x4.473°=176Z163VUu,=176/2sin(314t+163°)VU.=-jXJ=-j80x4.4Z73=352/-17VU+Uuc=352/2sin(314t-17°)Vu=220/2sin(314t+20°)V
例题解析已知：u=2202sin0tV，R=502，R=1002，X=2002，X=4002求：电流i、i、i。U=220Z0°VRR1UZ,=R, +jX, =(100 +j200)2220/0°i0.5/-33AU440Z33°Z点Z,=-jXc=-j4002-jX1iX.13Z,Z(100+j200)(-j400)=320+ j2401=0.8959.6°A1Z#=Z,+Z,Z,+Z2100+j200-j400OZ,Z=R+Z#==370+j240=440Z33Q1=0.5/93.8°Ai,=Z,+Z2i=0.5/2sin(0t-33°)Ai,=0.89V2sin(ot-59.6)Ai, = 0.5/2 sin(01 +93.8°)A