Question

In the circuit shown below, the cells A and B have negligible resistance. For $V_A=12V,R_1=500\Omega$ and $R=100\Omega$, the galvanometer (G) shows no deflection. The value of $V_B$ is:

• A. 4V
• B. 2V
• C. 12V
• D. 6V

Answer 1

The correct option is B 2V

In series voltage divides while current is same.
In parallel current divides while voltage is same.
Galvanometer show no deflection that implies no current passes through it, potential different drop across $R_1=$


$=V_A\frac{R_1}{R_1+R}=12\times \frac{500}{(500+100)}=10V$
Potential difference across R = 12 - 10 = 2V
$V_B=2V$ [R is parallel to $V_B$]