The dimensions of $RC$ are ($C$ and $R$ represent capacitance and resistance respectively).

In the given circuit,the internal resistance of the $18\,V$ cell is negligible. If $R_1 = 400\,\Omega$,$R_3 = 100\,\Omega$,and $R_4 = 500\,\Omega$,and the reading of an ideal voltmeter across $R_4$ is $5\,V$,then the value of $R_2$ will be ........... $\Omega$.

The battery in the diagram is to be charged by the generator $G$. The generator has a terminal voltage of $120 \ V$ when the charging current is $10 \ A$. The battery has an $emf$ of $100 \ V$ and an internal resistance of $1 \ \Omega$. In order to charge the battery at $10 \ A$ charging current,the resistance $R$ should be set at ................ $\Omega$.

$A$ battery of $e.m.f.$ $10 \, V$ and internal resistance $3 \, \Omega$ is connected to a resistor $R$ as shown in the figure. If the current in the circuit is $0.5 \, A$,then the resistance of the resistor $R$ will be ............. $\Omega$.

$A$ copper voltameter is connected to a $12 \, V$ source,and $2 \, g$ of copper is deposited in $30 \, min$. If this cell is connected to a $6 \, V$ source,how much copper (in $g$) will be deposited in $45 \, min$?

In the adjacent circuit,a voltmeter of internal resistance $R$,when connected across $B$ and $C$,reads $\frac{100}{3} \ V$. Neglecting the internal resistance of the battery,the value of $R$ is ................. $k \Omega$.