Question

To draw maximum current from a combination of cells, how should the cells be grouped?

• A. Series
• B. Parallel
• C. Mixed
• D. Depends upon the relative values of external and internal resistance

Answer 1

Answer: (D)

Current taken from the combination of $n$ cells each of internal resistance $r$ in series with external resistance $R$ is
$i=\frac{nE}{nr+R}$
Similarly, for parallel combination
$i=\frac{nE}{r+nR}$
For mixed grouping of $n$ such cells in $m$ rows with external resistance $R$ is
$i=\frac{mnE}{mR+nr}$
It is obvious that maximum current obtained from each combination depends on relative values of external and internal resistance.