thermocouple Questions

The temperature of inversion of a thermocouple is 620°C and the neutral temperature is 300°C. what is the temperature of cold junction ?

The rate of increase of thermo e.m.f. with temperature at the neutral temperature of a thermocouple:

A thermocouple of negligible resistance produces an $e.m.f.$ of $40\mu {\text{V/}}^{\circ }\text{C}$ in the linear range. A galvanometer of resistance $10\Omega$ with sensitivity $1\mu \text{A/div}$ is used. The smallest temperature difference detectable is: