$A$ copper voltameter is connected in parallel with a heater coil of resistance $0.1\,\Omega$. $A$ current is passed for $20\,\text{minutes}$,resulting in the deposition of $0.99\,\text{g}$ of copper on the cathode. If the electrochemical equivalent of copper is $0.00033\,\text{g/C}$,the heat produced in the coil is ........... $J$.

The charge flowing through a resistance $R$ varies with time according to $Q = at - bt^2$. The total heat produced in $R$ is: (assume that the direction of current is not reversed)

The temperature coefficient of resistance of tungsten is $4.5 \times 10^{-3} \, ^{\circ}C^{-1}$ and that of germanium is $-5 \times 10^{-2} \, ^{\circ}C^{-1}$. $A$ tungsten wire of resistance $100 \, \Omega$ is connected in series with a germanium wire of resistance $R$. The value of $R$ for which the resistance of the combination does not change with temperature is .......... $\Omega$.

In the circuit shown in the figure,find the current through the $4\,\Omega$ resistor.

Consider the following two statements $A$ and $B$,and identify the correct choice out of the given answers:
$A$. Thermo $e.m.f.$ is minimum at the neutral temperature of a thermocouple.
$B$. When two junctions made of two different metallic wires are maintained at different temperatures,an electric current is generated in the circuit.

In the circuit of the adjoining figure,the current through the $12 \ \Omega$ resistor will be ................ $A$.