If $E = at + bt^2$,what is the temperature of inversion?

$A$ thermocouple is made from two metals,Antimony and Bismuth. If one junction of the couple is kept hot and the other is kept cold,then,an electric current will

Two bulbs of $500\, W$ and $200\, W$ are manufactured to operate on a $220\, V$ line. What is the ratio of heat produced in the $500\, W$ bulb to the $200\, W$ bulb when they are connected in parallel,and when they are connected in series?

$A$ 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 ........... $J$.

In the circuit shown in the figure,the capacitor $C$ is initially uncharged and the key $K$ is open. In this condition,a current of $1 \,A$ flows through the $1 \,\Omega$ resistor. The key is closed at time $t=t_0$. Which of the following statement(s) is(are) correct?

[Given: $e^{-1}=0.36$]
$(A)$ The value of the resistance $R$ is $3 \,\Omega$.
$(B)$ The current through the $3 \,\Omega$ resistor (connected in parallel to the $1 \,\Omega$ and $R$ branches) is $2 \,A$ when $K$ is open.
$(C)$ At $t=t_0+7.2 \,\mu s$,the current in the capacitor branch is $0.6 \,A$.
$(D)$ For $t < \infty$,the charge on the capacitor is $12 \,\mu C$.

In the circuit shown in the figure,the $5\,\Omega$ resistance develops $20.00\,cal/s$ due to the current flowing through it. The heat developed in the $2\,\Omega$ resistance (in $cal/s$) is