What happens when current is passed in an antimony-bismuth couple? (1) The junction becomes hot when current flows from antimony to bismuth (2) The junction becomes hot when the current flows from bismuth to antimony (3) Both junctions become hot (4) Both junctions become cold.

Answer: (2) The junction becomes hot when the current flows from bismuth to antimony

In 1834, Peltier discovered that when an electric current is passed through a circuit of a thermocouple, heat is evolved at one junction and absorbed at the other junction. This is known as Peltier effect.

Based on the Peltier effect, the junction becomes hot when the current flows from bismuth to antimony.