Two cells,each of $e.m.f. \ E$ and internal resistance $r$,are connected in parallel across an external resistor $R$. If the power delivered to the resistor $R$ is maximum,then:

$A$ battery of $24$ cells,each of emf $1.5\,V$ and internal resistance $2\,\Omega$,is to be connected in order to send the maximum current through a $12\,\Omega$ resistor. The correct arrangement of cells will be:

The number of dry cells,each of $e.m.f.$ $1.5\,V$ and internal resistance $0.5\,\Omega$,that must be joined in series with a resistance of $20\,\Omega$ so as to send a current of $0.6\,A$ through the circuit is:

What is meant by the series connection of cells? Derive the equation for the equivalent electromotive force $(emf)$ of two cells with $emf$ $\varepsilon_1$ and $\varepsilon_2$ connected in series.

$N$ identical cells are connected in series or in parallel. When an external resistor $R$ is connected to them,they provide the same current. The internal resistance $r$ of each cell is:

$n$ rows,each containing $m$ cells in series,are connected in parallel. The maximum current is drawn from this combination through an external resistance of $3\, \Omega$. If the total number of cells used is $24$ and the internal resistance of each cell is $0.5\, \Omega$,then $m$ and $n$ are respectively: