Question

In balanced metre bridge, the resistance of bridge wire is $0.1Ω/\, cm$. Unknown resistance ‘$X$’ is connected in left gap and $6Ω$ in right gap, null point divides the wire in the ratio $2 : 3$. Find the current drawn from the battery of $5 \,V$ having negligible resistance.

• A. $1\,A$
• B. $1.5\,A$
• C. $2\,A$
• D. $5\,A$

Answer 1

Answer: (A)

Resistance of meter bridge $=100 \times 0.1=10 \,\Omega$
$\frac{x}{6}=\frac{2}{3} \rightarrow x=4 \Omega$
$\frac{1}{R_{t}}=\frac{1}{6+4}+\frac{1}{10} \rightarrow R_{T}=5$
$I=\frac{V}{R_{T}}=\frac{5}{5}=1 A$