Five cells each of emf $E$ and internal resistance $r$ are connected in series. Due to oversight,one cell is connected wrongly. The equivalent internal resistance of the combination is ........... $r$.

Electromotive force is actually not a force. What does it represent?

$A$ total of $100$ cells,each having an $emf$ of $5\,V$ and an internal resistance of $1\,\Omega$,are connected to an external resistance of $25\,\Omega$ to obtain the maximum current. If each row contains an equal number of cells,what should be the number of rows?

$10$ identical cells,each of potential $E$ and internal resistance $r$,are connected in series to form a closed circuit. What is the potential difference across any $3$ cells (in $E$)?

$A$ group of $N$ cells whose $emf$ varies directly with the internal resistance as per the equation $E_N = 1.5\, r_N$ are connected in series as shown in the figure. The current $I$ in the circuit is ........... $A$.

Two cells of emfs $1$ $V$ and $2$ $V$ and internal resistances $2 \Omega$ and $1 \Omega$ respectively are connected in parallel and provide a current of $1$ $A$ through an external resistance. If the polarity of one cell is reversed, the current through the external resistance becomes $\frac{\alpha}{5}$ $A$. The value of $\alpha$ is . . . . . . .