Question

The expression for thermo e.m.f. in a thermocouple is given by the relation $E\mspace{6mu} = \mspace{6mu} 40\mspace{6mu}\theta\mspace{6mu} - \mspace{6mu}\frac{\theta^{2}}{20}$, where θ is the temperature difference of two junctions. For this, the neutral temperature will be

• A. 100⁰ C
• B. 200⁰ C
• C. 300⁰ C
• D. 400⁰ C

Answer 1

Answer: (D)

400⁰ C

Answer 2

Comparing the given equation of thermo e.m.f. with E = α t + $\frac{1}{2}\beta t^{2}$ we get $\alpha = 40$ and $\beta = - \frac{1}{10}$.

By using $t_{n} = - \frac{\alpha}{\beta} \Rightarrow t_{n} = 400^{o}C$.