如图,两个闭合回路,用网孔电流法解题,关键点是通过 20Ω 电阻的电流是两个回路的电流代数和.(8+4+20) * I1 - 20 * 1 = 16I1 = 1.125 AUab = 1.125 * （4+20）- 1 * 3 = 24 VRab = 8 // 24 + 3 = 9ΩI = Uab / (Rab + RL) = 24 / (9+3) = 2 A
