$10$ cells,each of $emf$ $E$ and internal resistance $r$,are connected in series to a variable external resistance. The figure shows the variation of the terminal potential difference of their combination with the current drawn from the combination. The $emf$ of each cell is ................ $V$.

To get maximum current through a resistance of $2.5\,\Omega$,one can use $m$ rows of cells,each row having $n$ cells. The internal resistance of each cell is $0.5\,\Omega$. What are the values of $n$ and $m$ if the total number of cells is $45$?

$12$ cells,each having the same $emf$ $E$ and internal resistance $r$,are connected in series,but some cells are wrongly connected. This arrangement is connected in series with an ammeter and two additional cells (each of $emf$ $E$ and internal resistance $r$). The current is $3 \, A$ when the cells and the battery aid each other,and it is $2 \, A$ when they oppose each other. The number of cells wrongly connected is:

$n$ equal cells,each having emf $E$ and internal resistance $r$,are connected in a circuit with an external resistance $R$. If the same current flows in the circuit whether the cells are connected in series or in parallel,then:

The internal resistance of a cell depends on

What will be the ratio of the equivalent electromotive force (emf) of two cells connected in series to the equivalent emf of two cells connected in parallel?