In a post office box arrangement used to determine the value of an unknown resistance,the unknown resistance should be connected between:

As the switch $S$ is closed in the circuit shown in the figure,the current passed through it is .................. $A$.

Five current-carrying conductors meet at a point $P$. Based on the provided image,what is the magnitude and direction of the current in the fifth conductor connected to point $Q$?

Calculate the equivalent resistance between $A$ and $B$.

The figure shows a network of five resistances and two batteries. The current through the $30\,V$ battery is ............... $A$.

Two batteries $V_1$ and $V_2$ are connected to three resistors as shown below. If $V_1=2 \,V$ and $V_2=0 \,V$,then the current $I=3 \,mA$. If $V_1=0 \,V$ and $V_2=4 \,V$,then the current $I=4 \,mA$. Now,if $V_1=10 \,V$ and $V_2=10 \,V$,then the current $I$ will be ............ $\,mA$.