Question

The temperature of the cold junction of thermocouple is 0${}^o$C and the temperature of hot junction is T${}^o$C. The emf is $E=16T-0.04T^2\mu V$. The inversion temperature $T_i$ is

• A. ${300}^o$C
• B. ${200}^o$C
• C. ${500}^o$C
• D. ${400}^o$C

Answer 1

Answer: (D)

${400}^o$C

The inversion temperature ($T_i$) of a thermocouple is that temperature of hot junction, at which thermo emf becomes zero i.e.

At $T=T_i$, $E=0$

Putting these values in the given equation:

$E=16T-0.04T^2$

$0=16T_i-0.04T_i^2$

$0.04T_i^2=16T_i$

$T_i=16/0.04={400}^{o}C$