4、图示电路开关闭合后电容电流i_c( )的时间常数()

37、当R=10Ω,ωL=10Ω串联后外加电压为[10+20sin wt]V时,电流的有效值为________A.

36、若电路的电压u=[10+20sinwt-30°)+8sin(3wt-60°)]V,电流i=[3+6sin(wt+30°)+2sin5 wt]A,则该电路的平均功率为________W

35、若电压u=[30√2 sinwt+40√2 cos(3wt-2π/3)+40√2 cos(3wt+2π/3)]V,其中w=103rad/s,则电压u的有效值为________V.

34、当R=4Ω与1/( )=3Ω并联后的总电流为[2+3sin(wt+30°)]A时,其端电压为________V

33、当wL=4Ω与1/wC=36Ω并联后外加电压(18sin wt+3cos3wt)V时,总电流为________

32、当R=4Ω与1/( )=3Ω串联后外加电压为[60-25sin(wt+30°)]V时,电流为________A

31、当R=3Ω与wL=4Ω串联后外加电压为(45+30sin(ωt-30°))V时,电流为________A

30、感抗wL=3Ω与容抗1/( )=27Ω串联后,接到电流源(3sinwt-2cos3wt)A上,其端电压
为________

29、已知一电源电压为u( )=30√2sin wt+80√2sin(3wt+2π/3)+30√2sin 5wtV,则电源电压的有效值为________

28、某一端口网络的电压和电流为关联参考方向,其电压和电流分别为:
u ( ) =(16+25√2sinwt+4√2sin (3wt+30°) +√6sin (5wt+50°) )V