Question

The cold junction of a thermocouple is at $0^{o}C$ . The thermo e.m.f produced in the thermocouple is given by an equation $E=16T-0.04T^{2}V$, where T is the temperature of the hot junction. The temperature of inversion and neutral temperature of the thermocouple are

• A. ${200}^{0}C,{400}^{0}C$
• B. ${400}^{0}C,{200}^{0}C$
• C. ${200}^{0}C,{300}^{0}C$
• D. ${300}^{0}C,{200}^{0}C$

Answer 1

Answer: (B)

${400}^{0}C,{200}^{0}C$

Here, $E=16T-0.04T^2$

For the inversion temperature, $T=T_i$, $E=0$

So, $16T_i-0.04T_i^2=0$ or $T_i=16/0.04={400}^{o}C$

For the neutral temperature, $T=T_n$, $\frac{dE}{dT}=0$

So, $16-0.04\left(2T_n\right)=0$ or $T_n={200}^{o}C$