Physics·Thermal Physics · NSSCO 3.2.1
Measurement of temperature
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Temperature tells us how hot or cold something is — but how do we actually measure it? In this lesson we discover the clever idea behind every thermometer: a thermometric property that changes with temperature. We take apart a liquid-in-glass thermometer, set its scale with fixed points, meet sensitivity, range and linearity, convert to the Kelvin scale, and finish with the thermocouple for the hottest and fastest jobs.
What you'll learn in this lesson
By the end you should be able to (NSSCO Physics 3.2.1):
- Describe temperature as the degree of hotness of an object, and explain that it is not the same as heat energy
- Explain how a physical property that varies with temperature (a thermometric property) can be used to measure temperature, e.g. the volume of a liquid or the resistance of a metal
- Describe the structure and action of a liquid-in-glass thermometer, and explain how its structure affects range and sensitivity
- State the need for fixed points and identify the ice point (0 °C) and steam point (100 °C) of the Celsius scale
- Explain what is meant by the sensitivity, range and linearity of a thermometer
- Describe the advantages and disadvantages of mercury and alcohol as thermometric liquids
- Recall the concept of absolute zero and the Kelvin scale, and use T/K = T/°C + 273
- Describe the structure and action of a thermocouple and explain its use for high and rapidly-changing temperatures
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