In the circuit shown below, a student performing Ohm's law experiment accidentally connects the voltmeter and the ammeter as shown. The reading in the voltmeter will be close to .......... $V$.

$A$ wire of cross-section area $A$,length $L_1$,resistivity $\rho_1$ and temperature coefficient of resistivity $\alpha_1$ is connected to a second wire of length $L_2$,resistivity $\rho_2$,temperature coefficient of resistivity $\alpha_2$ and the same area $A$,so that the wires carry the same current. The total resistance $R$ is independent of temperature for small temperature changes if (Thermal expansion effect is negligible):

In how much time will one litre of ${H_2}$ be collected by a $5\, A$ current? (Given: $Z = 1 \times {10^{ - 8}}\,kg/C$ and density of ${H_2} = 0.09\,kg/{m^3}$)

In the adjoining figure,the $emf$ of the cell is $2 \, V$ and its internal resistance is negligible. The resistance of the voltmeter is $80 \, \Omega$. The reading of the voltmeter will be ................ $volt$.

$A$ $d.c.$ main supply of $e.m.f. \, 220 \, V$ is connected across a storage battery of $e.m.f. \, 200 \, V$ through a resistance of $1 \, \Omega$. The battery terminals are connected to an external resistance $'R'$. The minimum value of $'R'$ so that a current passes through the battery to charge it is ............... $\Omega$.

In the circuit shown,$n$-identical resistors $R$ are connected in parallel $(n > 1)$ and the combination is connected in series to another resistor $R_0$. In the adjoining circuit,$n$ resistors of resistance $R$ are all connected in series along with $R_0$. The batteries in both circuits are identical and the net power dissipated in the $n$ resistors in both circuits is the same. The ratio $R_0 / R$ is