Q. In the circuit shown, a $meter$ bridge is in its balanced state. The $meter$ bridge wire has a resistance $0.1\ ohm/cm.$ The value of unknown resistance $X$ and the current drawn from the battery of negligible resistance is
A) $6\ \Omega,\ 5\ amp$
B) $10\ \Omega,\ 0.1\ amp$
C) $4\ \Omega,\ 1.0\ amp$
D) $12\ \Omega,\ 0.5\ amp$
Explanation
(c) Resistance of the part $AC$
$R_{AC} = 0.1 \times 40 = 4\Omega$ and $R_{CB} = 0.1 \times 60 = 6\Omega$
In balanced condition $\frac{X}{6} = \frac{4}{6} \Rightarrow X = 4\Omega$
Equivalent resistance $R_{eq} = 5\Omega$ so current drawn from battery
$i = \frac{5}{5} = 1A$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.