Essay On Seebeck Effect

Thermoelectric effects

The thermoelectric effect is direct conversion of temperature differences to electric voltage and vice versa which comprises of the Seebeck effect and the Peltier effect.

2.3.1 Seebeck effect

Seebeck effect is named after the German physicist Thoman Johann Seebeck whom discovered it in 1821. Seebeck effect basically is the concept of conversion of temperature differences into electricity. He first discovered this when he found circuit made from two dissimilar metals with junctions at different temperatures would deflect a compass magnet. He initially believed that this was due to magnetism induced by the temperature difference. It was later that he realized that this was due to an electric current induced that deflected the compass [12].

The term Seebeck Coefficient of a material is the measurement of the magnitude of an induced thermoelectric voltage in response to a temperature difference across a material with the unit of voltage per degree celcius (V/oC) [12]. Seebeck coefficient are often denoted by S or σ and is a non-linear as a function of temperature and is dependent on the conductors’ absolute temperature, material and molecular structure. The table 2.1 shows some of the seebeck coefficient for some elements. Table 2.1:

Typically, p-type semiconductor material has positive Peltier coefficient while n-type material has negative Peltier coefficient. This shows that the Peltier effect in fact has the reversed physics of Seebeck effect. One way to understand the phenomenon of Peltier effect is that, when electrons flow from a region of high density to a region of low density, they try to maintain electron equilibrium that existed before the current was applied, by absorbing energy at one end and emitting it at the other. A series of these thermocouples can be connected in order to enlarge the effect