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 $V_A-V_B=6V$

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