Question

Three batteries of emf $1V$ and internal resistance $1\Omega$ each are connected as shown. Effective emf of the combination between the points $P$ and $Q$ is

• A. zero
• B. $1V$
• C. $2V$
• D. $\frac{2}{3}V$

Answer 1

Answer: (A)

The given circuit is

Equivalent emf is given by
${\epsilon }_{eq}=\frac{2\times 1}{2+1}=\frac{2}{3}$
we have,
$\frac{E_{eq}}{{\epsilon }_{eq}}=\frac{E_1}{{\epsilon }_1}-\frac{E_2}{{\epsilon }_2}$
$\frac{{\epsilon }_{eq}}{\left(\frac{2}{3}\right)}=\frac{2}{2}-\frac{1}{1}$
$\Rightarrow E_{eq}=0$volt