Question

In the given electrical circuit, the potential difference between points A and B is (assume the battery is ideal and the conducting wires have almost zero resistance) :

• A. 5 V
• B. 10 V
• C. 25 V
• D. 70 V

Answer 1

Answer: (A)

5 V

Redrawing the given circuit we obtain a Wheatstone's network. Hence current through 5 ohm resistor is zero.

Now series equivalent of resistors is:
$\frac{R}{2}+\frac{R}{2}=R$

Current through $R$ is:
$I_R=\frac{10}{R}$

Also current through resistor $\frac{R}{2}$ is,
$I_r=\frac{10}{R}$

Potential difference between A and B is:
$V=\left(\frac{10}{R}\right)\frac{R}{2}=5V$