Physics - Current Electricity Question with Solution | TestHub

$\begin{array}{c}\text{Wire-joined nodes: }J,K.\\ \text{Left: three branches }R,\\ \text{two corner branches }2R.\\ \frac{1}{R_{AJ}}=\frac{3}{R}+\frac{1}{2R}+\frac{1}{2R}\\ R_{AJ}=\frac{R}{4}\\ \text{Right: five parallel }R.\\ R_{JK}=\frac{R}{5}\\ R_{AB}=R_{AJ}+R_{JK}\\ R_{AB}=\frac{9R}{20}\\ R=20\Omega \\ R_{AB}=9\Omega \end{array}$