Question

In circuit shown below, the resistances are given in ohm and the battery is assumed ideal with emf equal to $3V$ . 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 $R_{eq}=75\Omega$
$\therefore$ 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