question_answer

A uniform wire of resistance 9 W is cut into 3 equal parts.  They are connected in the form of equilateral triangle ABC.  A cell of e.m.f. 2 V and negligible internal resistance is connected across B and C.  Potential difference across AB is [Kerala (Engg.) 2001]

A)         1 V

B)                        2 V

C)         3 V                                    

D)         0.5 V

Correct Answer: A

Solution :

                                         The circuit can be drawn as follows Equivalent resistance \[R=\frac{3\times (3+3)}{3+(3+3)}=2\Omega \] Current \[i=\frac{2}{2}=1A.\] So,\[{{i}_{1}}=1\times \left( \frac{3}{3+6} \right)=\frac{1}{3}A\].         Potential difference between A and B =\[\frac{1}{3}\times 3=1volt.\]