Question

In circuit shown below, the resistances are given in ohm and the battery is assumed ideal with emf equal to $ 3\,V $ . The voltage across the resistance $R_{4}$ is

• A. 0.4 V
• B. 0.6 V
• C. 1.2 V
• D. 1.5 V

Answer 1

Answer: (A)

Equivalent resistance of the given network $R_{e q}=75\, \Omega$
$\therefore $ Total current through battery,
$i=\frac{3}{75} i_{1}=i_{2}=\frac{3}{75 \times 2}=\frac{3}{150}$
Current through resistance
$R_{4}=\frac{3}{150} \times \frac{60}{(30+60)}$
$=\frac{3}{150} \times \frac{60}{90}=\frac{2}{150} A$
$V_{4}=i_{4} \times R_{4}=\frac{2}{150} \times 30$
$=\frac{2}{5}=0.4$ volt