When the switch $S$, in the circuit shown, is closed, then the value of current $i$ will be ................. $A$.

The potential difference between points $C$ and $D$ of the electrical circuit shown in the figure is (in $V$)

The value of current through the $5 \Omega$ resistor of the given circuit is

Two batteries,one with an $emf$ of $3\,V$ and internal resistance $1\,\Omega$,and the other with an $emf$ of $15\,V$ and internal resistance $2\,\Omega$,are connected in series with a resistance $R$ as shown in the figure. If the potential difference between points $a$ and $b$ is zero,find the resistance $R$ in $\Omega$.

In the circuit shown in the adjoining figure,the current between $B$ and $D$ is zero. The unknown resistance $X$ is ................ $\Omega$.

For the circuit shown in the figure,the current through the $6 \Omega$ resistor connected between the junctions $A$ and $B$ is (in $A$)