In the circuit shown the cells $A$ and $B$ have negligible resistances. For $V_A=12 \mathrm{~V}$, $R_1=500…
In the circuit shown the cells $A$ and $B$ have negligible resistances. For $V_A=12 \mathrm{~V}$, $R_1=500 \Omega$ and $R=100 \Omega$ the galvanometer (G) shows no deflection. The value of $V_B$ is
$4 \mathrm{~V}$
$2 \mathrm{~V}$
$12 \mathrm{~V}$
$6 \mathrm{~V}$
Solution
Applying Kirchhoff's law
$500 I+100 I=12$
So, $I=\frac{12 \times 10^{-2}}{6}=2 \times 10^{-2}$
Hence, $V_B=100\left(2 \times 10^{-2}\right)=2 \mathrm{~V}$
