$A$ primary cell has an $e.m.f.$ of $1.5\,V$. When short-circuited,it gives a current of $3\,A$. The internal resistance of the cell is ............. $\Omega$.

Three identical cells,each of emf $10 \ V$ and internal resistance $3 \ \Omega$,are connected in parallel across terminals $A$ and $B$. The net emf across $A$ and $B$ is .......... $V$.

$A$ cell of internal resistance $r$ is connected to an external resistance $R$. The current will be maximum in $R$,if

$N$ 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:

$A$ resistance $R$ is connected to $n$ identical cells. If the current in the resistance is the same whether the cells are connected in series or in parallel,then the internal resistance $r$ of each cell is: