Module 4 : THERMOELECTRICITY
Lecture 21 : Seebeck Effect
Example
  Compute the thermo-emf of a copper-constantan thermocouple with its junctions at $0^\circ$ C and $100^\circ$ C.
  Solution
 
From the table above we have ${\cal E}_{Cu-Pt} = +760\ \mu V$ and ${\cal E}_{Cn-Pt} = -3510\ \mu V $. Thus
 
\begin{eqnarray*} {\cal E}_{Cu-Cn} &=& {\cal E}_{Cu-Pt}-{\cal E}_{Cn-Pt}\\ &=& 760 - (-3510) = 4270 \mu V \end{eqnarray*}
  Thus the emf yield of a copper-constantan thermocouple is 4.27 mV.
  Exercise
  The thermoelectric power of a thermocouple whose cold junction is maintained at $0^\circ$ C and the hot junction at $t^\circ$ C is given by the following graph.
(1)
 Sketch the thermo-emf with temperature.
(2)
 Determine the neutral temperature and the temperature of inversion. How will these two temperatures change if the cold junction were maintained at $50^\circ$ C ?

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