Question

When cold junction is at $0^{0}C$ and hot junction is at ${100}^{0}C$, thermo emfs developed by Fe - Pb and Pb - Bi thermocouples are 650 $\mu$ V and 450 $\mu$ V respectively. Thermo emf developed for Fe - Bi thermocouple per $1^{0}C$ temperature difference is

• A. $1100\mu V$
• B. $550\mu V$
• C. $11\mu V$
• D. $200\mu V$

Answer 1

The correct option is C $11\mu V$

We have emf $E=S\Delta T$(S is the Seebeck coefficient)
Thus for Fe-Pb we have $650=S_1\times 100$
or
$S_1=6.5$
and for Pb Bi we have $450=S_2\times 100$
or
$S_2=4.5$
Thus the Seebeck coefficient for Fe Bi will be $S_1+S_2=11$
Thus we get emf for Fe Bi as $11\times 1=11\mu V$