Question

How is thermal emf generated?

(a) when current flows

(b) when voltage is applied

(c) when the null detector is connected

(d) when dissimilar metals come in contact

The question was posed to me in final exam.

My doubt is from Measurement Errors in a Wheatstone Bridge topic in section Measurement of Resistance of Electrical Measurements

Answer 1

Correct choice is (d) when dissimilar metals come in contact

The best I can explain: When dissimilar metals come into contact with each other in a galvanometer circuit, thermal emf is generated. Null detector is used for detecting the balance condition.