初等/五等/佐級◆基本電學大意題庫下載題庫

先化簡電路

Rt = ((5+15)//20)+2 = 12歐姆

I = 36/12 = 3A

2歐姆消耗功率 = I^2*R = 3*3*2 = 18W

電流分流，兩邊各流1.5A

20歐姆消耗功率 = 1.5*1.5*20 = 45W

5歐姆消耗功率 = 1.5*1.5*5 = 11.25W

15歐姆消耗功率 = 1.5*1.5*15 =33.75W

故20歐姆消耗功率最大