$A$ cell of $emf$ $E$ and internal resistance $r$ is connected in series with an external resistance $nr$. Then,the ratio of the terminal potential difference to $emf$ is

$A$ $100 \ V$ voltmeter having a resistance of $20 \ k\Omega$ is connected in series with a very high resistance $R$. When it is connected to a $110 \ V$ line,it reads $5 \ V$. What is the value of $R$?

$A$ current of $1.5\, A$ flows through a copper voltameter. The thickness of copper deposited on the electrode surface of area $50\, cm^2$ in $20\, min$ will be (Density of copper $= 9000\, kg/m^3$ and $E.C.E.$ of copper $= 0.00033\, g/C$).

$A$ thermocouple of resistance $1.6\,\Omega$ is connected in series with a galvanometer of $8\,\Omega$ resistance. The thermocouple develops an e.m.f. of $10\,\mu V$ per degree temperature difference between two junctions. When one junction is kept at $0\,^{\circ}C$ and the other in a molten metal,the galvanometer reads $8\,mV$. The temperature of the molten metal,when e.m.f. varies linearly with temperature difference,will be ............ $^{\circ}C$.

Twelve wires of equal length and equal cross-sectional area form a cube. If the resistance of each wire is $R$,then the effective resistance between the two ends of a diagonal is:

The resistance of a voltameter is $2\,\Omega$. It is connected in series to a battery of $10\,V$ through a resistance of $3\,\Omega$. In a certain time,the mass deposited on the cathode is $1\,g$. Now,the voltameter and the $3\,\Omega$ resistance are connected in parallel with the battery. The increase in the deposited mass on the cathode in the same time will be .............. $g$.