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

$A$ galvanometer is connected in series with an unknown resistor $R$ and two identical batteries of $1.5\, V$ each. When the batteries are connected in series,the galvanometer shows a current of $1\, A$. When the batteries are connected in parallel,it shows a current of $0.6\, A$. The internal resistance of each battery is:

In the circuit shown,the potential difference between $A$ and $B$ is ............. $V$.

$100$ cells, each of $e.m.f.$ $5\, V$ and internal resistance $1\, \Omega$, are to be arranged to produce maximum current in a $25\, \Omega$ external resistance. Each row must contain an equal number of cells. The number of rows should be:

The circuit in the figure shows two cells connected in opposition to each other. Cell $E_1$ has an $emf$ of $6 \ V$ and an internal resistance of $2 \ \Omega$. Cell $E_2$ has an $emf$ of $4 \ V$ and an internal resistance of $8 \ \Omega$. Find the potential difference between the points $A$ and $B$.

The reading of a high resistance voltmeter when a cell is connected across it is $2.2\, V$. When the terminals of the cell are also connected to a resistance of $5\,\Omega$,the voltmeter reading drops to $1.8\, V$. Find the internal resistance of the cell in $\Omega$.