In the given circuit diagram,the galvanometer reading is zero. If the internal resistance of the cell is neglected,then the value of $X$ is ......... $\Omega$.

Two resistances of $400 \Omega$ and $800 \Omega$ are connected in series with a $6 \text{ V}$ battery of negligible internal resistance. $A$ voltmeter of resistance $10000 \Omega$ is used to measure the potential difference across the $400 \Omega$ resistor. The error in the measurement of potential difference in volts is approximately:

For ensuring the dissipation of the same energy in all three resistors $(R_1, R_2, R_3)$ connected as shown in the figure,their values must be related as:

If each resistance in the figure is of $9\,\Omega$,then the reading of the ammeter is ............ $A$.

$A$ cell of emf $6\, V$ and internal resistance $0.5\, \Omega$ is short-circuited. The current in the cell is ............... $A$.

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