The $n$ rows each containing $m$ cells in series are joined in parallel. Maximum current is taken from this combination across an external resistance of $3 \,\Omega$ resistance. If the total number of cells used are $24$ and internal resistance of each cell is $0.5 \,\Omega$ then
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(c) Total cells = $m × n = 24 $.... $(i)$
For maximum current in the circuit $R = \frac{{mr}}{n}$
$==>$ $3 = \frac{m}{n} \times (0.5)$
$==>$ $m = 6n$ ..... $(ii)$
On solving equation $(i)$ and $(ii)$, we get $m = 12, n =2$
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