Assertion : $A$ larger dry cell has higher $emf$.
Reason : The $emf$ of a dry cell is proportional to its size.

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 .............. $J/s$.

Two sources of equal emfs $E$ are connected in series. This combination is connected to an external resistance $R$. The internal resistances of the two sources are $r_{1}$ and $r_{2}$ $(r_{1} > r_{2})$. If the potential difference across the source of internal resistance $r_{1}$ is zero,then the value of $R$ will be:

The internal resistance of a cell of emf $4 \text{ V}$ is $0.1 \ \Omega$. It is connected to an external resistance of $3.9 \ \Omega$. The terminal voltage across the cell will be . . . . . . . (in $\text{ V}$)

Two cells are connected between points $A$ and $B$ as shown. Cell $1$ has an emf of $12 \, V$ and an internal resistance of $3 \, \Omega$. Cell $2$ has an emf of $6 \, V$ and an internal resistance of $6 \, \Omega$. An external resistor $R$ of $4 \, \Omega$ is connected across $A$ and $B$. The current flowing through $R$ will be $............. \, A$.

$12$ cells,each having the same emf $E$ and internal resistance $r$,are connected in series and kept in a closed box. Some of the cells are wrongly connected. This battery is connected in series with an ammeter and two cells,each identical to the previous cells. The current is $3 \, A$ when the external cells aid the battery and $2 \, A$ when the external cells oppose the battery. How many cells in the battery are wrongly connected?