4c2(0.) 0.1 R2+ s+5×104 I(5)=I1(s)+I2(s)=-0.2 故电容电压为 uc(0) U()=是4()+ 30 ss+5×10 U()=c()+"0) 30 20 s+5×104 则开关断开后电路的总电流i和电容上电压uc,uc分别为 (t)=0.2 A c(t)=(30-10e30)v lc(t)=(30-20e×102)V