In the shown circuit,what is the potential difference across $A$ and $B$ (in $V$)?

Consider the circuit shown. If all the cells have negligible internal resistance,what will be the current through the $2 \Omega$ resistor when steady state is reached (in $A$)?

The figure shows currents in a part of an electric circuit. Then the current $I$ is: (in $A$)

$A$ Wheatstone's bridge is balanced with a resistance of $625\, \Omega$ in the third arm,where $P, Q$ and $S$ are in the $1^{st}, 2^{nd}$ and $4^{th}$ arm respectively. If $P$ and $Q$ are interchanged,the resistance in the third arm has to be increased by $51\,\Omega$ to secure balance. The unknown resistance in the fourth arm is ............. $\Omega$.

Four ammeters with identical internal resistances $r$ and a resistor of resistance $R$ are connected to a current source as shown in the figure. It is known that the reading of the ammeter $A_1$ is $I_1 = 3\ A$ and the reading of the ammeter $A_2$ is $I_2 = 5\ A$. Determine the ratio of the resistances $R/r$.

In the adjoining circuit,the galvanometer $G$ shows zero deflection. If the batteries $A$ and $B$ have negligible internal resistance,the value of the resistor $R$ will be .............. $\Omega$.