Question

In the circuit shown the cells $A$ and $B$ have negligible resistances. For $V_{A}=12 V , R_{ i }=500 \Omega$ and $R=100 \,\Omega$ the galvanometer ( $G$ ) shows no deflection. The value of $V_{B}$ is

• A. 4 V
• B. 2 V
• C. 12 V
• D. 6V

Answer 1

Answer: (B)

Since the galvanometer shows no deflection so current will flow as shown in the figure.

Current, $I=\frac{V_{A}}{R_{1}+R}=\frac{12 V }{(500+100) \Omega}=\frac{12}{600} A$
$V_{B}=I R=\left(\frac{12}{600} A \right)(100 \Omega)=2 V$