Q.
Figure shows a circuit with known resistances $R_{1}$ .Neglect the internal resistance of the sources of current and resistance of the connecting wire. The magnitude of electromotive force $E_{1}$ such that the resistances $R\ $ is zero will be
A) $ER_{1}/R_{2}$
B) $ER_{2}/R_{1}$
C) $E\left( R_{1} + R_{2} \right)/R_{2}$
D) $ER_{1}/(R_{1} + R_{2})$
Explanation
(c) Current through resistance $R$ will be zero if
$\frac{E}{R_{2}} = \frac{E_{1}}{R_{1} + R_{2}}or\ E_{1} = \frac{E(R_{1} + R_{2})}{R_{2}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.