In the adjoining circuit, the battery $E_1$ has an $e.m.f.$ of $12 \, V$ and zero internal resistance, while the battery $E_2$ has an $e.m.f.$ of $2 \, V$. If the galvanometer $G$ reads zero, then the value of the resistance $X$ in $ohms$ is

$A$ copper wire of radius $0.1 \text{ mm}$ and resistance $2 \text{ k}\Omega$ is connected across a power supply of $40 \text{ V}$. The number of electrons transferred per second between the supply and the wire at one end is

The equivalent resistance between $A$ and $B$ is ............ $\Omega$.

When the terminals of a cell are connected by a wire of resistance $4 \Omega$,the potential difference across the cell is $1.6 \text{ V}$. If a wire of the same resistance is connected in parallel with the first,the potential difference becomes $1.33 \text{ V}$. The emf and internal resistance of the cell are respectively

As shown,the circuit is made of $8$ different resistors. It is found that when $R_1 = 4\,\,\Omega,$ the resistance between $A$ and $B$ is $2\,\,\Omega.$ Now replace $R_1$ by a $6\,\,\Omega$ resistor,what is the resistance between $A$ and $B$?

The reading of the voltmeter in the circuit shown is ............. $V$. (in $.25$)