The temperature of the cold junction and the neutral temperature of a thermocouple are $15\,^{\circ}C$ and $280\,^{\circ}C$ respectively. The temperature of inversion is .............. $^{\circ}C$.

Two heating coils, one of fine wire and the other of thick wire of the same material and of the same length, are connected in series and in parallel. Which of the following statements is correct?

$A$ 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 $n\,?$

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

Assertion : All electric devices shown in the circuit are ideal. The reading of each of ammeter $(A)$ and voltmeter $(V)$ is zero.
Reason : An ideal voltmeter draws almost no current due to very large resistance, and hence $(V)$ and $(A)$ will read zero.

The temperature of the cold junction of a thermocouple is $0\,^oC$ and the temperature of the hot junction is $T\,^oC$. The thermo e.m.f. is given by the relation $E = AT - \frac{1}{2}BT^2$ (where $A = 16$ and $B = 0.08$). The temperature of inversion is ............... $^oC$.