左下圖電路之等效 T 型電路如右下圖所示,求 R1、R2 與 R3 各為多少 Ω?

AR1 = 1 Ω,R2 = 4 Ω,R3 = 0.8 Ω正確答案
BR1 = 0.8 Ω,R2 = 4 Ω,R3 = 1 Ω
CR1 = 2 Ω,R2 = 10 Ω,R3 = 8 Ω
DR1 = 10 Ω,R2 = 8 Ω,R3 = 2 Ω
答案與詳解

π→T轉換:令Ra=2Ω(左並聯)、Rb=8Ω(右並聯)、Rc=10Ω(上串聯),分母=2+8+10=20。R1=Ra×Rc/(Ra+Rb+Rc)=2×10/20=1Ω;R2=Rb×Rc/(Ra+Rb+Rc)=8×10/20=4Ω;R3=Ra×Rb/(Ra+Rb+Rc)=2×8/20=0.8Ω,完全符合。
