Question

The ratio of the equivalent resistance of the network (shown in figure) between the points a and $b$ when switch is open and switch is closed is $x : 8$. The value of $x$ is ____

Answer 1

$R _{ eq \text { open }}=\frac{3 R }{2}$
$R _{ eq \text { closed }}=2 \times \frac{ R \times 2 R }{3 R }=\frac{4 R }{3}$
$\frac{ R _{ eq \text { open }}}{ R _{ eq \text { closed }}}=\frac{3 R }{2} \times \frac{3}{4 R }=\frac{9}{8}$
$\therefore x =9$