Question

The thermo emf of a thermocouple is given by $E\left(t\right)=40t-\frac{t^2}{20}$, where $t$ is the temperature of hot junction and the cold junction being kept at $0^{o}C$. What is the neutral temperature of the thermocouple ?

• A. ${400}^{o}C$
• B. ${300}^{o}C$
• C. ${200}^{o}C$
• D. ${100}^{o}C$

Answer 1

The correct option is A ${400}^{o}C$

When a potential difference is applied between the ends of a conductor, current begins to flow through it. The current flows as conductor contains large number of free electrons which begin to drift from the end at lower potential to the end at higher potential. In the process they constantly keep on colliding with atoms of conductor. The atoms gain energy and begin to vibrate more vigorously about their mean position. Thus the average kinetic energy of atoms of conductor increases. This results in a rise in the temperature of the conductor and we say that the conductor has been heated. Thus, flow of current has a heating effect on the conductor.