The internal resistance of a primary cell is $4\,\Omega$. It generates a current of $0.2\,A$ in an external resistance of $21\,\Omega$. The rate at which chemical energy is consumed in providing the current is .............. $J/s$.

$N$ identical cells are connected in series or in parallel. When an external resistor $R$ is connected to them,they provide the same current. The internal resistance $r$ of each cell is:

Infinite number of cells having $emf$ and internal resistance $(E, r)$,$(\frac{E}{n}, \frac{r}{n})$,$(\frac{E}{n^2}, \frac{r}{n^2})$,$(\frac{E}{n^3}, \frac{r}{n^3})$... are connected in series across an external resistance of $\frac{nr}{n+1}$. The current flowing through the external resistor is:

To get the maximum current from a parallel combination of $n$ identical cells,each of internal resistance $r$,connected to an external resistance $R$,which of the following conditions must be satisfied?

The potential difference across a cell and the current through it are shown in the graph. $A$ battery consists of $40$ such identical cells. The maximum current supplied by the battery through a load of $2.5\,\Omega$ is equal to .............. $A$.

It is easier to start a car engine on a hot day than on a cold day. This is because the internal resistance of the car battery