Question

Four resistances $4\Omega ,6\Omega ,18\Omega$ and $8\Omega$ are connected in arms AB, BC, CD and DA respectively of Wheat stone's network. The shunt resistance across $18\Omega$ to balance the network is _________.

• A. $12\Omega$
• B. $16\Omega$
• C. $18\Omega$
• D. $36\Omega$

Answer 1

The correct option is D $36\Omega$

If the bridge is to be balanced then:

If a resistance is $R$ is put in parallel across $18\Omega$, the effective resistance in arm AD will be $\frac{18R}{18+R}$
$\frac{4}{6}=\frac{8}{18\times R/(18+R)}\Rightarrow R=36\Omega$