如题所述
解题:(1)R1=U1’/I2=9V/0.45A=20Ω
(2) ∵U1/U1’=I1R1/I2R1=3V/9V I2=0.45A
∴I1/I2=1/3
∴I1=0.15A
I1/I2=(R1+R2)/(R1+R2+R3)=1/3
∴R3=2(R1+R2)=80Ω
(3)U=I2(R1+R2)=0.45A(20Ω+20Ω)=18V