Question

For what value of $R$ in the circuit as shown current passing through $4 \,\Omega $ resistance will be zero

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

Answer 1

Answer: (A)

When the current through $4\, \Omega $ resistance is zero,
then $V_{A}-V_{B}=6\,V$

i.e., the potential difference across $2\,\Omega $ resistance would be $10-6=4\,V$
$\therefore $ Current through $2\,\Omega $ resistance is $2\,A$ .
The potential difference across $R$ is $\left(6 - 4\right)V$ and $2\,A$ flows through it
$\overset{}{\Rightarrow } \, R \, =\frac{6 - 4}{2}$
$\therefore R=1\,\Omega $