Physics - Current Electricity Question with Solution | TestHub

The situation can be depicted as shown in figure.As resistances $S$ and $6\Omega$ are in parallel their effective resistance is $\frac{6S}{6+S}\Omega$ As the bridge is balanced, hence it is balanced Wheatstone's bridge. For balancing condition, $\begin{array}{rlrl}& & \frac{P}{Q}& =\frac{R}{\left(\frac{6S}{6+S}\right)}\\ \text{ or }& & \frac{2}{2}& =\frac{2(6+S)}{6S}\\ \text{ or }& & 3S& =6+S\\ \text{ or }& & S& =3\Omega \end{array}$