Physics - Current Electricity Question with Solution | TestHub

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