Question

In Iron-copper thermo couple, below the inversion temperature at cold junction, electric current flows from

• A. Iron to copper
• B. Copper to iron
• C. No current flows
• D. May be in any direction

Answer 1

Answer: (B)

Copper to iron

Thermoelectric Series : Sb, Fe, Cd, Zn, Ag, Au,Cr, Sn, Pb, Hg, Mn, Cu, Pt, Co, Ni, Bi

Thermoelectric emf is directly proportional to the distance between the two metals.

Farther metals provide the maximum emf. If two metals in the series from a thermocouple, current flows at the cold junction from the metal that comes earlier in the series to the metal later in the series.

In the case of copper-iron thermocouple, the current flows from copper(Cu) to Iron(Fe) at the cold junction below the temperature of inversion.