First,a set of $n$ equal resistors of $10 \; \Omega$ each are connected in series to a battery of emf $20 \; V$ and internal resistance $10 \; \Omega$. $A$ current $I$ is observed to flow. Then,the $n$ resistors are connected in parallel to the same battery. It is observed that the current is increased $20$ times. The value of $n$ is .... .

$A$ battery consists of a variable number $n$ of identical cells (each having electromotive force $\varepsilon$ and internal resistance $r$) which are connected in series. The terminals of the battery are short-circuited and the current $I$ is measured. Which of the graphs shows the correct relationship between $I$ and $n\,?$

Two different metals are joined end to end. One end is kept at a constant temperature and the other end is heated to a very high temperature. The graph depicting the thermo $e.m.f.$ $(E)$ versus temperature $(t)$ is:

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 .......... $\Omega$.

$A$ thermocouple produces $200\,\mu V$ between $0\,^oC$ and $100\,^oC$. If it produces $64\,\mu V$ and $76\,\mu V$ for temperature ranges $(0\,^oC - 32\,^oC)$ and $(32\,^oC - 70\,^oC)$ respectively,then the thermo $emf$ produced between $70\,^oC$ and $100\,^oC$ will be ........... $\mu V$.

The total power dissipated in the circuit shown here is ............. $W$.