设网孔电流
3Ω·Ib 1Ω·Ia-1Ω·Ic=0
3Ω·Ic-1Ω·Ib 1Ω·Ia 4V=0
Ia=2A
解得Ib=-1.5A Ic=-2.5A
U1=-Ib·1Ω=1.5A
U2=(Ib-Ic)·1Ω=1V