Step 1: Ensure that the temperature-dependent substance has a physical property which varies linearly with temperature. This property must change evenly and continuously with temperature changes.
Step 2: Choose two standard temperatures which are easily obtainable and reproducible. Normally, the temperatures of pure melting ice and steam at one atmospheric pressure are chosen as the fixed points. Record the values of the physical property of the substance at these two fixed points.
Step 3: Set up a scale by dividing the temperature range between the two fixed points into a fixed number of equal parts (or degrees) to obtain a scale.
16. Two bodies are in thermal equilibrium. What does this statement mean?
When the two bodies are in thermal equilibrium, it means that there is no exchange of heat energy between these two bodies/or no net flow of heat energy from one to another. The temperatures for both bodies are the same.
17. (a) Describe the principal features of a thermocouple thermometer.
The principal features of a thermocouple thermometer is the usage of two types of wires made of different metals, joined together to form two junctions. The temperature is then calculated using the readings of the voltmeter. The greater the difference in temperature, the greater the voltage produced across the ends of the two junctions, i.e the higher reading registered in voltmeter. The thermometer is hence calibrated by having one end of the junction kept at a fixed temperature and the other junction is then used as a tiny probe to measure other temperatures
(b) State why the thermodynamic scale of temperature is called an absolute scale.
A thermodynamic scale of temperature is called an absolute scale as it measures the lowest possible temperature which exists in the universe, the absolute zero. Absolute zero is the temperature at which all possible thermal energy has been transferred away from the body, i.e K.E of molecule = 0.