Physics - Current Electricity Question with Solution | TestHub

The equivalent circuit can be redrawn asWe have, $\frac{P}{Q}=\frac{R}{S}$ i.e, $\frac{4}{4}=\frac{4}{4}$ So, the given circuit is a balanced Wheatstone's bridge. Hence, the equivalent resistance $\begin{array}{rl}{R}_{AB}& =\frac{(4+4)\times (4+4)}{(4+4)+(4+4)}=\frac{8\times 8}{8+8}\\ & =\frac{64}{16}=4\Omega \end{array}$