Question

The galvanometer shows no deflection. What is the resistance x

• A. $6\Omega$
• B. $3\Omega$
• C. $12\Omega$
• D. None of these

Answer 1

The correct option is C $12\Omega$

For null condition, $\frac{P}{Q}=\frac{S}{R}$
Here, $P=6||x=\frac{6x}{6+x},Q=6,S=2,R=3$
thus, $\frac{6x}{(6+x)6}=\frac{2}{3}$
or $6x=24+4x$
or $2x=24\Rightarrow x=12\Omega$