question_answer

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: [JEE Main Online Paper (Held On 11 April 2015)]  

A)  3V

B)  4V

C)  5V

D)  6V

Correct Answer: C

Solution :

  If current in \[4\Omega \] is zero then \[\underset{BCDE}{\mathop{{{\varepsilon }_{v}}}}\,=0\] \[{{V}_{EB}}+{{V}_{BC}}+{{V}_{CD}}+{{V}_{DE}}=0\] \[-4+3+{{V}_{CD}}+0=0\] \[{{V}_{CD}}=1\]volt again \[{{V}_{A}}-9+3+1-{{V}_{D}}=0\] \[{{V}_{A}}-{{V}_{D}}=5V\]