Q. A battery consists of a variable number (n) of identical cells, each having an internal resistance r connected in series. The terminal of the battery is short-circuited. A graph of current $versus$ the number of cells will be as shown in figure
A) [image:3_image127.emf]
B) [image:3_image128.emf]
C) [image:3_image129.emf]
D) [image:3_image130.emf]
Explanation
(c) For a two cell battery
$I = \frac{2E}{2r} = \frac{E}{r}$
Similarly, for a $n$ cell battery
$I = \frac{nE}{nr} - \frac{E}{r}$
So, current in the circuit does not depend on number of cells in the battery.
Hence, the correct graph will be (c).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.