$A$ current of $2\,A$ is flowing through a cell of $e.m.f.$ $5\,V$ and internal resistance $0.5\,\Omega$ from negative to positive electrode. If the potential of the negative electrode is $10\,V$,the potential of the positive electrode will be .............. $V$.

$A$ storage battery is connected to a charger for charging with a voltage of $12.5 \text{ V}$. The internal resistance of the storage battery is $1 \ \Omega$. When the charging current is $0.5 \text{ A}$,the $EMF$ of the storage battery is: ............... $\text{volts}$

The $e.m.f.$ of a cell is $6 \ V$. When a current of $2 \ A$ flows through it,the potential difference across its terminals is $3 \ V$. The internal resistance of the cell is ............. $\Omega$.

Two cells of emf $1 \ V$ and $2 \ V$ and internal resistance $2 \ \Omega$ and $1 \ \Omega$,respectively,are connected in series with an external resistance of $6 \ \Omega$. The total current in the circuit is $I_1$. Now the same two cells in parallel configuration are connected to the same external resistance. In this case,the total current drawn is $I_2$. The value of $\left(\frac{I_1}{I_2}\right)$ is $\frac{x}{3}$. The value of $x$ is . . . . . . .

$n$ identical cells are joined in series,with two cells $A$ and $B$ in the loop having reversed polarities. The $EMF$ of each cell is $E$ and the internal resistance is $r$. The potential difference across cell $A$ or $B$ is (where $n > 4$):

Write the equation for the equivalent electromotive force (emf) of a series connection of cells.