Question

A graph is drawn between the temperature difference between the junctions (x-axis) and thermo emf on y-axis. Then,
a) it is a parabola.
b) it is hyperbola.
c) its slope at any point gives thermoelectric power.
d) its slope at any point on it gives Seebeck coefficient.

• A. a and c are true
• B. b and d are true
• C. a, c and d are true
• D. b,c and d are true

Answer 1

The correct option is C a, c and d are true

The relation between the thermoelectric power (e) and the temperature difference ($\theta$) between two junction is given by:

$e=a\theta +b{\theta }^2$, where a and b are material specific constants.

So this is a parabola (option 1)

Differentiating this equation :

$\frac{de}{d\theta }=a+2b\theta$, this is called thermoelectric power (Option c).

This is also called Seebeck coefficient (Option d).