In the circuit shown in the figure,the reading of the voltmeter is $V_1$ when only $S_1$ is closed,and the reading of the voltmeter is $V_2$ when only $S_2$ is closed. The reading of the voltmeter is $V_3$ when both $S_1$ and $S_2$ are closed. Then:

For which value of resistance $R$ does the galvanometer show zero deflection in the electrical circuit shown below (in $\Omega$)?

$50\,\Omega$ and $100\,\Omega$ resistors are connected in series. This combination is connected to a battery of $2.4\,V$. When a voltmeter of $100\,\Omega$ resistance is connected across the $100\,\Omega$ resistor,the reading of the voltmeter will be ............. $V$.

By a cell,a current of $0.9\, A$ flows through a $2\, \Omega$ resistor and $0.3\, A$ flows through a $7\, \Omega$ resistor. The internal resistance of the cell is ............ $\Omega$.

Find the current through the $2\,\Omega$ resistance in the given circuit. (in $A$)

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: