Fermocouple Analysis

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ANALYSIS OF THE SEEDBECK EFFECT OF SOME THERMOCOUPLES A.S. Ogungbe*, O.O. Babalola, E.O Onori, C.O. Ogabi, O.A. Adejo Department of Physics, Lagos State University, Ojo, Lagos, Nigeria *Email: ogungbea@yahoo.co.uk
ABSTRACT
A thermocouple is a temperature-measuring device that consists of two dissimilar conductors that are joined at each end. In this experiment, two junctions were created between two different materials; Nichrome and Constantan, Copper and Constantan, and Nichrome and Copper, by twisting the wires firmly together. The voltmeter leading to the two free ends was set to the most sensitive DC voltage (200 mV). The voltage was measured and recorded with both junctions at room temperature. One junction was inserted into an ice block at 0oC, while the other junction was inserted into hot liquid maintained at 100oC and the voltage was measured and recorded. The procedure was repeated using different pairs of materials to create the junctions with various lengths and diameters of the wires, with a view to determining the pair that will generate the
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The first way is applying an electric field to a material with no temperature gradient. This defines the electrical conductivity (σ) of the materials by taking the ratio between the current density and the applied electric field. The second way is applying a temperature gradient and measuring the heat flow. This defines the thermal conductivity (k) of the material by taking the ratio of heat flow to unit area. The third way is applying a temperature gradient across two dissimilar homogeneous conductive materials. This defines the Seebeck coefficient (thermopower, thermoelectric power) by taking the ratio between the voltage produced (Seebeck voltage) and the temperature difference (Rowe,

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