更新时间2019-03-09 15:22:48
求Is
1、U1 = 0.2Is,10U1 = 2Is;中间支路两端电压 = 2 * 40 = 80 v,5Ω电阻两端电压 = 80 + 2Is;
5Ω电阻电流 i = ( 80 + 2Is )/5 = 16 + 2Is/5;
Is = i + 2 = 18 + 2Is/5,3Is/5 = 18,Is = 30 A 。
2、用戴维宁定理
U1 = 0.2Is,10U1 = 2Is,所以,等效电压 = 5Ω压降 - 10U1 = 5Is - 2Is = 3Is;
等效电阻 = 5Ω;
I = 3Is/( 40 + 5 ) = 2,Is = 90/3 = 30 A 。