Consider the circuit shown in the figure where all the resistances are of magnitude $1 k \Omega$. If the current in the extreme right resistance $X$ is $1 mA$, the potential difference between $A$ and $B$ is: (in $V$)

In the given circuit,the galvanometer reading is zero. If the internal resistance of the cells is negligible,then the value of $x$ is ............. $\Omega$.

In a Wheatstone bridge,three resistors $P$,$Q$,and $R$ are connected in three arms,and the fourth arm is formed by the parallel combination of two resistors $S_1$ and $S_2$. The condition for the bridge to be balanced is:

Two cells of voltage $10 \ V$ and $2 \ V$ and internal resistances $10 \ \Omega$ and $5 \ \Omega$ respectively,are connected in parallel with the positive end of $10 \ V$ battery connected to the negative pole of $2 \ V$ battery (figure). Find the effective voltage and effective resistance of the combination.

In the following diagram,the Wheatstone bridge is balanced when we interchange the resistances of:

$A$ battery of $6\,V$ is connected to the circuit as shown below. The current $I$ drawn from the battery is: