Q. Two identical cell send the same current in $2\Omega$ resistance, whether connected in series or in parallel. The internal resistance of the cell should be
A) $1\ \Omega$
B) $2\ \Omega$
C) $\frac{1}{2}\Omega$
D) $2.5\ \Omega$
Explanation
(b) In series, $i_{1} = \frac{2E}{2 + 2r}$
In parallel, $i_{2} = \frac{E}{2 + \frac{r}{2}} = \frac{2E}{4 + r}$
Since $i_{1} = i_{2} \Rightarrow \frac{2E}{4 + r} = \frac{2E}{2 + 2r} \Rightarrow r = 2\Omega$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.