Nr串电阻=3A*6R - 2A*4R / (6-2-3)=10RNr并电阻=3A*6R / 6A-2A-3A =18R Nr并右支路等效R=10R*18R / 10R+18R=6.43R4R右边等效R=Nr串电阻+Nr并右支路等效R=16.43R6R右边等效R=4R*4R右边等效R / 4R+4R右边等效R=3.2RI总=12V / 6R+6R右边等效R=12/9.2=1.3AU1=6R*I总=6*1.3=8V