The $V-i$ graphs for a conductor at temperatures $T_1$ and $T_2$ are shown. $(T_2 - T_1)$ is proportional to:

If two wires having resistance $R$ and $2R$ are joined in series and then in parallel,what is the ratio of heat generated in these two situations,assuming the same voltage is applied?

$A$ brass disc and a carbon disc of same radius are assembled alternatively to make a cylindrical conductor. The resistance of the cylinder is independent of the temperature. The ratio of thickness of the brass disc to that of the carbon disc is [$\alpha$ is temperature coefficient of resistance and neglect linear expansion].

For a thermocouple,the neutral temperature is $270\,^\circ C$ and the temperature of its cold junction is $20\,^\circ C$. If there is no deflection in the galvanometer,the temperature of the hot junction should be .............. $^\circ C$

Above neutral temperature,thermo $e.m.f.$ in a thermocouple

$A$ cell of emf $E$ is connected to a resistance $R_{1}$ for time $t$ and the amount of heat generated in it is $H$. If the resistance $R_{1}$ is replaced by another resistance $R_{2}$ and is connected to the cell for the same time $t$, the amount of heat generated in $R_{2}$ is $4H$. Then the internal resistance $r$ of the cell is: