Physics - Current Electricity Question with Solution | TestHub

The network is symmetric under exchange of the top and bottom nodes, so those two nodes are equipotential and can be merged.

After merging: A-side has two $1\Omega$ in parallel = $0.5\Omega$; the two $4\Omega$ give $2\Omega$ to the midpoint; the two $2\Omega$ give $1\Omega$ to B.

The midpoint branch is $2+3=5\Omega$ in series, parallel with the $1\Omega$: $\frac{5\times 1}{5+1}=\frac{5}{6}\Omega$.

Total: $R_{AB}=0.5+\frac{5}{6}=\frac{4}{3}\Omega$.