Question

In the circuit shown in figure, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be

• A. 1000 $\omega$
• B. 500 $\omega$
• C. 100 $\omega$
• D. 200 $\omega$

Answer 1

Answer: (C)

100 $\omega$

Current through $R$ is $12/(500+R)$

Voltage across R is $\frac{12R}{500+R}$

Since galvanometer shows zero deflection, so

$\frac{12R}{500+R}=2$ or $R=100\omega$