Organizational part - 5 minutes. Rollcall of the students and elucidation the reasons of the absence of students, checking of theRollcall of the students and elucidation the reasons of the absence of students, checking of the conspectus. Number of forming competencies:knowledge, practical skills, legal competence Main questions of the theme: 45 minutes 1. What is the temperature coefficient of resistance and on what does it depend in case of metals and semiconductors? 2. The main advantages of electronic thermometers. 3. Calculation of unknown resistance using the Wheatstone bridge.
Break - 10 minutes Learning and teaching methods: - analysis and discussing of main and control questions; - discussing of the results of laboratory tasks performance; - testing; - drawing a graph. Methods of the control of formed at classes competencies: - testing on a computer (a student has to give the answers for test questions that contain minimal knowledge and skills – main definitions, theoretical questions of the theme); - performance of the laboratory work, calculations of mistakes and presenting of the measurement results in graphical view; - dispute; - work with devices and observance of safety engineering at the work with them. Students’ independent work - 30 minutes To learn how to graduate thermistor and thermocouple. Task 1: 1. Construct the scheme of installation. 2. Mark the initial temperature of water 3. Write the value of thermal resistance Rt to the table. 4. Heating the water till the boiling conduct the resistance measurement of thermistor in every 10оС. 5. Obtained data write to the table 1. 6. Draw the graph of the dependence of conductors resistance on the temperature 7. Determine the thermal coefficient of resistance by the formula:
Task 2: 1. Immerse the ends of thermocouple to the vessels with water and measure the temperature in both vessels. 2. Heating the water till boiling conduct the measurement with galvanometer in every 10оС, write the number of division which were rejected by galvanometer needle to the table 2. 3. Determine the sensitivity of thermocouple by the formula:
4. Draw the graph of the dependence
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in the vessel that contains thermal resistance and heater, balance the bridge.
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and make a conclusion.
