Question

The potential difference between points $A$ and $B$ is:

• A. $\frac{20}{7}V$
• B. $\frac{40}{7}V$
• C. $\frac{10}{7}V$
• D. zero

Answer 1

Answer: (D)

From the given figure, current through lower branch of resistances which are joined in series is
$i_1=\frac{10}{4+3}=\frac{10}{7}$ amp

Again current through upper branch of resistances which are also connected in series, is
$i_2=\frac{10}{8+6}=\frac{10}{14}amp$
Now according to the Kirchhoff's voltage law
$V_B-V_A=8\times i_2-4\times i_1$
$=8\times \frac{10}{14}-4\times \frac{10}{7}=0$