Looking for classes? Ksquare Career Institute, Bengaluru →
In the circuit shown the cells A and B have negligible resistances. For $V_A$ = 12 V, $R_1$ = 500 $\Omega$ and R = 100 $\Omega$ the galvanometer (G) shows no deflection. The value of $V_B$ is
A
6 V
B
4 V
C
2 V
D
12 V
Detailed Solution
With no current through the galvanometer, cell A drives a current through $R_1$ and R in series.
$i = \frac{12}{500 + 100} = \frac{12}{600} = \frac{1}{50}$ A
Potential difference across R $= 100\times\frac{1}{50} = 2$ V
For null deflection $V_B$ equals this potential difference: $V_B = 2$ V
$i = \frac{12}{500 + 100} = \frac{12}{600} = \frac{1}{50}$ A
Potential difference across R $= 100\times\frac{1}{50} = 2$ V
For null deflection $V_B$ equals this potential difference: $V_B = 2$ V