Question

In the given circuit diagram, the value of resistance $X$ in ohm when the bridge is balanced will be -

• A. $4$
• B. $8$
• C. $10$
• D. $12$

Answer 1

The correct option is B $8$

The resistance $8\Omega$ and $X$ are in parallel combination and let their equivalent resistance be $R$.

For wheat-stone bridge to be balanced-

$\frac{10}{4}=\frac{10}{R}$

$⟹R=4\Omega$

And, $\frac{1}{R}=\frac{1}{8}+\frac{1}{X}$ since, they are parallel

$⟹\frac{1}{X}=\frac{1}{4}-\frac{1}{8}=\frac{1}{8}$

$⟹X=8\Omega$

Answer-(B)