Question

In the given circuit, find the value of R(in $\Omega$), for which current through 4$\Omega$ resistor is zero. ___

Answer 1

$V_A-V_B=6V$, for current in 4$\Omega$ resistor to be zero.
Pot. diff. across 2$\Omega$ resistor = 10 – 6 = 4V
Current through 2$\Omega$ resistor = 2A
So, $2=\frac{netemf}{netresistance}=\frac{(10-4)}{(2+R)}$
$R=5\Omega$