The GATE Grind

GATE 2026 IN – Question 30

Sensors and Industrial Instrumentation · Temperature and analytical sensors · 1 mark · Multiple select

Which of the following statements is/are correct for a thermocouple?

  1. It is based on the Seebeck Effect.
  2. The change in resistance is measured.
  3. The voltage difference between the two junctions is linearly proportional to the temperature difference between the junctions.
  4. It is based on the concept of Joule Heating.

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Show answer and explanation

Correct answer: (A) It is based on the Seebeck Effect.

Explanation

A thermocouple generates an emf through the Seebeck effect, so **A** is correct.

It measures voltage rather than a resistance change, so B is false. Its emf is generally a nonlinear function of the junction temperatures; proportionality is a limited-range approximation, so the unqualified statement C is false. Joule heating is not its operating principle, so D is false.

Select **A only**.