Question

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

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

Hint:

Nichrome-Constantan → high Seebeck coefficient near 273 K → used in precise temperature sensing.

Answer 1

The Correct Option is B

In instrumentation engineering, a thermocouple pair's sensitivity at a specific temperature is determined by the Seebeck effect, which is the generation of an electromotive force (EMF) in response to a temperature gradient between two dissimilar metals. The sensitivity of a thermocouple, expressed in microvolts per degree Celsius (μV/°C), depends on the materials used.

At around 273 K (0°C), the sensitivity of various thermocouple pairs can differ significantly. In this case, the thermocouple pair that provides the maximum sensitivity is Nichrome-Constantan. This suggests that the thermal and electrical properties of Nichrome and Constantan make them particularly effective at generating a measurable EMF around this temperature, making the pair highly sensitive for instrumentation purposes.

Therefore, choosing a Nichrome-Constantan pair for applications requiring high sensitivity at low temperatures is optimal due to its superior performance compared to the other listed options.