In the given circuit,the value of $i$ is ........... $A$.

$A$ non-zero current passes through the galvanometer $G$ shown in the circuit when the key $K$ is closed and its value does not change when the key is opened. Then,which of the following statement$(s)$ is/are true?

Three resistances $P, Q, R$ each of $2 \,\Omega$ and an unknown resistance $S$ form the four arms of a Wheatstone bridge circuit. When a resistance of $6 \,\Omega$ is connected in parallel to $S$,the bridge gets balanced. What is the value of $S$ in $\Omega$?

Kirchhoff's loop law represents the conservation of which physical quantity?

The equivalent resistance between $A$ and $B$ in the given circuit is . . . . . . . . (in $Omega$)

The value of the resistance $R$ in the figure is .......... $\Omega$.