Question

In the electric network shown, when no current flows through the $4\, \Omega$ resistor in the arm $EB$, the potential difference between the points $A$ and $D$ will be :

• A. 3 V
• B. 4 V
• C. 5 V
• D. 6 V

Answer 1

Answer: (C)

$i_{4}=0$
Using Kirchhoff's law:
$g -2 i-2-2 i-4=0 ; 3-4 i=0; i=3 / 4 A$
$4-i R-3=0$
$\Rightarrow i R =1 ;$
$V_{ AD }=2 i-2-2 i=0$
$\Rightarrow V_{ AB }=2+4 i=2+\left(\frac{3}{4}\right)=5\, V$