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The below table provides the thermos-emf sensitivity of five materials with reference to platinum around 273 K. Material Constantan Nickel Copper Iron Nichrome Sensitivity (μVK-1) -35 -25 +6 +18.5 +25 Which one of the following thermocouple pairs has maximum sensitivity around 273 K?

The below table provides the thermos-emf sensitivity of five materials with reference to platinum around 273 K. Material Constantan Nickel Copper Iron Nichrome Sensitivity (μVK-1) -35 -25 +6 +18.5 +25 Which one of the following thermocouple pairs has maximum sensitivity around 273 K? Correct Answer Nichrome-constantan

A thermocouple is a sensor for measuring temperature. It consists of two dissimilar metals, joined together at one end. When the junction of the two metals is heated or cooled a voltage is produced that can be correlated back to the temperature.

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

Material

Constantan

Nickel

Copper

Iron

Nichrome

Sensitivity (μVK-1)

-35

-25

+6

+18.5

+25

 

Sensitivities of different thermocouple pairs are:

Nichrome-constantan: 25 – (-35) = 60 μV/K

Copper-Nickel: 6 – (-25) = 31 μV/K

Platinum-constantan: -35 μV/K

Nickel-constantan: -25 – (-35) = 10 μV/K

Therefore, Nichrome-constantan has highest sensitivity.

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