Q. $n$ identical cells, each of emf $E$ and internal resistance $r$, are connected in series a cell $A$ is joined with reverse polarity. The potential difference across each cell, except $A$ is
A) $\frac{2nE}{n - 2}$
B) $\frac{(n - 2)E}{n}$
C) $\frac{(n - 1)E}{n}$
D) $\frac{2E}{n}$
Explanation
(d) When one call is wrongly connected in series, the emf of cells decrease by $2\ E$, but internal resistance of cells remains the same for all the cells.
Current in the circuit is $i = \frac{(n - 2)E}{nr} \times r$
Potential difference across each cell is
$V = E - Ir = E - \frac{(n - 2)E}{nr} \times r = \frac{2E}{n}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.