等效电路是1Ω,1Ω,2Ω三个电阻并联,再和4Ω的电阻串联.立起来的那个2Ω的电阻被短路,可以拿掉.
Rab=(1×1×2)/(1×1+1×2+1×2)+4
=0.4+4
=4.4Ω
说明:R1,R2,R3的并联电阻R=R1R2R3/(R1R1+R2R3+R3R1)
等效电路是1Ω,1Ω,2Ω三个电阻并联,再和4Ω的电阻串联.立起来的那个2Ω的电阻被短路,可以拿掉.
Rab=(1×1×2)/(1×1+1×2+1×2)+4
=0.4+4
=4.4Ω
说明:R1,R2,R3的并联电阻R=R1R2R3/(R1R1+R2R3+R3R1)