Question

Two sources of emf $6\, V$ and internal resistance $3\, \Omega$ and $2\, \Omega$ are connected to an external resistance $R$ as shown. If potential difference across terminal of battery $A$ is zero, then value of $R$ is

• A. $1\, \Omega$
• B. $2\, \Omega$
• C. $3\, \Omega$
• D. $4\, \Omega$

Answer 1

Answer: (A)

Potential difference across battery ;
$\Delta V=6-3I $ Given $\Delta V=0$.
$I=2 ; I=\frac{12}{5+R}$
$\Rightarrow 5 \times 2+2 R=12$
$\Rightarrow 2 R=2 $
$\Rightarrow R=1$