The $e.m.f.$ of a cell is generally........

Two identical cells,when connected either in parallel or in series,give the same current in an external resistance of $5\,\Omega$. The internal resistance of each cell will be $.............\,\Omega$.

Two sources of equal $emf$ $(\varepsilon)$ are connected in series to an external resistance $R$. The internal resistances of the two sources are $R_1$ and $R_2$ $(R_2 > R_1)$. If the potential difference across the source having internal resistance $R_2$ is zero, then:

The $e.m.f.$ of a lead-acid car battery is $12 \, V$. The internal resistance of the battery is $0.5 \, \Omega$. The maximum current that can be drawn from the battery is ............. $A$.

Why is the combination of cells done? Write its methods.

The $e.m.f.$ of a primary cell is $2 \ V$. When it is short-circuited,it gives a current of $4 \ A$. The internal resistance of the primary cell is ............. $\Omega$.