Analog Circuit Design

30

Thermocouple measurement

Jim Williams

Introduction

In 1822, Thomas Seebeck, an Estonian physician, accidentally joined semicircular pieces of bismuth and copper (Figure 30.1) while studying thermal effects on galvanic arrangements. A nearby compass indicated a magnetic disturbance. Seebeck experimented repeatedly with different metal combinations at various temperatures, noting relative magnetic field strengths. Curiously, he did not believe that electric current was flowing, and preferred to describe the effect as “thermo-magnetism.” He published his results in a paper, “Magnetische Polarisation der Metalle und Erze durch Temperatur-Differenz” (see references).

Figure 30.1 The Arrangement for Dr. Seebeck’s Accidental Discovery of “Thermo-Magnetism” ...