1.电源电压U=I(R1+R2)=0.3×40=12(v)
2.I1=U/R1=12/30=0.4(A)
I2=U/R2=12/10=1.2(A)
I总=I1+I2=0.4+1.2=1.6(A)
两问回答完毕.