When the capacitor is fully charged,find the current drawn from the $9\, V$ cell (in $mA$).

Resistances of $6\, \Omega$ each are connected in the manner shown in the adjoining figure. With the current $0.5\, A$ as shown in the figure, the potential difference $V_P - V_Q$ is .............. $V$.

$A$ copper voltameter and a silver voltameter are connected in parallel. When a total charge $q$ flows through the voltameters,an equal mass of metal is deposited in each. If the electrochemical equivalents of copper and silver are $z_1$ and $z_2$ respectively,then the charge flowing through the silver voltameter is:

One end each of a resistance $r$,a capacitor $C$,and a resistance $2r$ are connected together. The other ends are respectively connected to the positive terminals of batteries $P$,$Q$,and $R$ having emfs $E$,$E$,and $2E$. The negative terminals of the batteries are then connected together. In this circuit,with steady current,the potential drop across the capacitor is:

The figure shows a network of resistances in which the point $A$ is earthed. The current through the $4\,\Omega$ resistor is

When a battery sends an electric current through a resistor $R_1$ for time $t$,the heat produced in the resistor is $Q$. When the same battery sends an electric current through a resistor $R_2$ for the same time $t$,the heat produced in the resistor $R_2$ is also $Q$. Determine the internal resistance $r$ of the battery.