Q. A thermocouple is made from two metals, Antimony and Bismuth. If one junction of the couple is kept hot and the other is kept cold, then, an electric current will
A) Flow from Antimony to Bismuth at the hot junction
B) Flow from Bismuth to Antimony at the cold junction
C) Not flow through the thermocouple
D) Flow from Antimony to Bismuth at the cold junction
Explanation
(d) When a circuit is made up on any two metals in thermoelectric series, the current flows across the cold junction from the later occurring metal in the series to the one occurring earlier. In thermoelectric series Bismuth comes earlier than Antimony. So, at cold junction current flows from Antimony to Bismuth and at hot junction it flows from bismuth to Antimony.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.