Find VAB from the circuit if all the resistances are of same value of 1 Ω.
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Fig. 20(a)
Redraw the Fig. 20(a), we have
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Fig. 20(b)
The resistance P and Q are in Series, the equivalent resistance R1=1+1=2Ω
The resistance R1 and R are in parallel. The equivalent resistance R2=(2×1)/(2+1)=2/3 Ω
Similarly the resistance U and T are in series and equivalent resistance R3=1+1=2 Ω.
The resistance R2 and s are in series and equivalent resistance R4=2/3+1=5/3 Ω. Finally the resistance R3 and R4 are in parallel each other. Hence total resistance between terminal A and B is
RTot=(5/3×2)/(5/3+2)=10/11 Ω
Hence VAB=1×10/11=10/11 Amp.
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Fig.22(a)