Physics - Current Electricity Question with Solution | TestHub

The circuit can be simplified as shown in the above figure. Due to symmetry, we can see that the distribution of current at point A in the circuit, is the same as the recombination of the current before point B. Also, the junction which is present between the points C and D can be disconnected because it won't affect the distribution of current.

$r_{\text{AB}}=r+\text{1.5}\mathit{\text{r}}+r$

$\Rightarrow r_{\mathrm{AB}}=\text{3.5}\mathit{\text{r}}=7 \mathrm{\Omega }$