那么,Um = (5-2)*4/3 = 4V,红线左边等效电阻 R = Um/I = 2Ω;
因为 U=2V=Um/2,所以 R2 = R1//R3;R = 2R2//R4;
所以,加上电流源后,红线左边电路等效为:
Um=(Is1+Is2)*R//R5=8V,I = Is2 - Um/R5= -1A;