Antimony and bismuth are usually used in a thermocouple,because

$A$ $3\,^oC$ rise in temperature is observed in a conductor by passing a certain current. When the current is doubled,the rise in temperature will be ............. $^oC$.

The direction of current in an iron-copper thermocouple is

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 .............. $^\circ C$

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

For a given temperature difference,which of the following pairs will generate maximum thermo $e.m.f.$?