Question

The table provides the thermo-emf sensitivity of five materials with reference to platinum around 273 K.

Material	Constantan	Nickel	Copper	Iron	Nichrome
Sensitivity$\mu V{K}^{-1}$	-35	-25	+6	+18.5	+25

The thermocouple pair that gives the maximum sensitivity around 273 K is

• A. Platinum - Constantan
• B. Nichrome - Constantan
• C. Nickel - Constantan
• D. Copper - Nickel

Answer 1

The correct option is B Nichrome - Constantan

	Thermocouple pair	Sensitivity
A	Platinum - Constantan	$0-(-35)=35\mu V/K$
B	Nichrome - Constantan	$25-(-35)=60\mu V/K$
C	Nickel - Constantan	$-25-(-35)=10\mu V/K$
D	Copper - Nickel	$6-(-25)=31\mu V/K$

So, maximum sensetivity is for Nichrome - constantan thermocouple