Question

A circuit is shown in the figure. The e.m.f. of the battery is

• A. 4 V
• B. 6 V
• C. 12 V
• D. 8 V

Answer 1

Answer: (C)

Equivalent resistance and current in the circuit has been calculated in the figures given below
In series, $R_{eq}=1+1=2\Omega$
In parallel, $R_{eq}=\frac{2\times 2}{2+2}=1\Omega$

In series, $R_{eq}=2+1=3\Omega$

In series$R_{eq}=\frac{6\times 3}{6+3}=2\Omega$

In series, $R_{eq}=2+2=4\Omega$

$\therefore$ emf, $E=$ (Total current) $\times$ (Net equivalent resistance)
$=3\times 4=12V$