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INDIANA UNIVERSITY, DEPARTMENT OF PHYSICS, P309 LABORATORY Laboratory #27: Peltier Elements and Thermistors Goal: Use of a temperature transducer, experimental study of an electrical heat pump. Measurement of heat flow. Equipment: Trygon 20V, 10A DC power supply, var. thermistors, MELCOR Peltier elements, glass thermometer, CIC 305 thermocouple thermometer, thermometers, vacuum jar with feed throughs, stop watch. (A) Physics: In this experiment we measure temperature, using various methods, including the old- fashioned glass thermometer, a commercial thermocouple probe and thermistors. Thermistors are resistors with a strongly temperature-dependent resistance. The relation between the temperature (in K) and the resistance (in k ) can be expressed by the empirical expression T ( R ) = [ A 0 + A 1 ln( R ) + A 2 (ln( R )) 3 ] -1 , (1) where the A i are constants that are typical for a given thermistor. Thus, a measurement at three different temperatures is necessary to determine these constants, and to calibrate the device. In a Peltier element, n-type and p-type semiconductor material is arranged as is shown in fig.1. Its upper and lower contacts are at temperatures T 1 and T 2 . When a current flows as indicated, positive and negative charge carriers both move from up to down. The flux of carriers is proportional to the current. Each carrier has
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This note was uploaded on 01/20/2012 for the course P 309 taught by Professor Urheim during the Spring '11 term at Indiana.

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