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Internet Remote Laboratory

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Physical Internet-controlled experiments

Grammar-school of J. Vrchlicky, Klatovy

úvod experimenty o laboratoři kontakt odkazy

Temperature dependence of the resistance of metals and semiconductors

Apparatus - measurement principle

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Subsequent measurement principle is based on a gradual cooling and warming of two elements. The first is a platinum resistance sensor whose resistance increases linearly with temperature. The second element is a thermistor, a semiconductor device whose resistance decreases exponentially with temperature. The change in temperature of both elements provides the so-called Peltier cells, one side of the passage of current is always cool and the other heats. This allows us to change the size and direction of flow reaching different temperatures. In our attempt to achieve an approximate temperature range from –5 °C až 65 °C (depending on conditions in the laboratory). Right image shows the view of the experimental device attached thermometer.


Both sensors are selected so that at room temperature was approximately the same resistance (about 1 kΩ). Resistances of both components are measured and displayed Ohmmeter connected directly to the panel remote tasks on the Web site of the experiment. The temperature of both sensors is measured with a thermometer and a digital display showing the thermometer, which, together with a task monitor user using a webcam.

control panel

Measurement is performed so that they always set the temperature of Peltier cells (to be prepared 12 values). After stabilizing the temperature and resistance values of elements subtract the actual value of temperature from a Web camera into the form and sends the measurements into the table - see at left. Values in the table can be directly on a Web page displayed in a graph indicative or download to your computer, where they can continue to be processed. The selected file format is CSV* - the file can be simply load in MS Excel and OO Calc. We can process data as needed in the spreadsheet. We can also further the results presented.

* CSV file is a standard text file, in which columns of data separated by a semicolon.

Control of the experiment
  1. Temperature setting - temperature can be adjusted through 12 prepared by the values

  2. Experimental values - resistor values are loaded automatically, the temperature should be read from a web camera

  3. Webcam - camera observing the display of digital thermometer with a temperature of measured element

  4. writing values to the table - measured values are entered into the table

  5. table of experimental values - t, Rk a Rp

  6. work with data in Table - see chart, save data, delete table

control panel

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