BlueNorth2012-04-30TA获得超过117个赞关注(1)此时为R1和R2串联电源电压=(R1+R2)*I=30欧*0.2A=6V因为R1:R2=1:2所以U1:U2=1:2(串联分压)所以R1两端电压为2V(2)此时为R1和R3并联，R2被短路R总=R1并R3=U源/I=6V/0.9A=20/3欧=6.67欧U1=U3=U源=6V所以I1=U1/R1=6V/10欧=0.6AI3=I总-I1=0.9-0.6=0.3A