Question

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. 4 V
• B. 2 V
• C. 12 V
• D. 6V

Answer 1

Answer: (B)

2 V

Answer 2

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

Current, $I = \frac{V_A}{R_1+R} = \frac{12\, V}{(500+100)\,\Omega}=\frac{12}{600}\, A$
$V_B=IR=\bigg( \frac{12}{600}A\bigg) (100\, \Omega)=2\, V$