Another method of measuring temperature involves color changes in temperature-sensitive organic materials. These are usually only useful for measuring limited temperature ranges, such as fever indication or room temperature monitoring. Another device, called thermistor, works based on changes in electrical resistance of a semiconductor material due to its temperature, according to Penn State (opens in a new window). These devices can detect extremely small temperature changes and are used in bolometers (opens in a new window) – measuring radiation as a function of a change in temperature – and to monitor laboratory experiments. However, no action would be possible without relying on the principle outlined in the zero law. You yourself do not use the expression „zero law of thermodynamics“ here. There are many statements of the same physical ideas in the physical literature long before this text, in very similar language. The only novelty here was the law of thermodynamics. Long before the term „zero law“ was coined, Maxwell[5] discussed ideas at length in 1871, which he summarized with the words „All warmth is of the same art“.
[5] Modern theorists sometimes express this idea by postulating the existence of a unique one-dimensional heat manifold in which each correct temperature scale has a monotonic map. [14] This can be expressed by stating that there is only one type of temperature, regardless of the variety of scales in which it is expressed. Another modern expression of this idea is that „all diathermic walls are equal.“ [6]: 23 This could also be expressed as meaning that there is exactly one type of non-mechanical, non-transferring contact equilibrium of matter between thermodynamic systems. Two systems in thermal contact eventually reach a state of thermal equilibrium. This state is clearly defined by temperature, which is a universal function of state properties and internal energy. If system 1 is in equilibrium with system 2 and if system 2 is in equilibrium with system 3, then system 1 is in equilibrium with system 3. This is called the zero law of thermodynamics and involves the construction of a universal temperature scale (first given by Joseph Black in the 18th century and named much later by Guggenheim). If a system is in thermal equilibrium, it is assumed that the energy is clearly distributed over the volume. As the system energy increases, the system temperature also increases (dU/dT> 0). The zero law states that if two thermodynamic systems are in thermal equilibrium with each other and also separately in thermal equilibrium with a third system, the three systems are in thermal equilibrium with each other. [1] [2] [3] When the zero law was originally conceived in the 18th century, there were already two laws of thermodynamics.
However, this new law, which introduced a formal definition of temperature, replaced existing laws and should rightly top the list, according to OpenStax (opens in a new window), an educational organization at Rice University. This led to a dilemma: the original laws were already well known by their assigned numbers, and the renumbering would create a conflict with the existing literature and cause considerable confusion. A scientist, Ralph H. Fowler (opens in a new window), found a solution to the dilemma: he called the new law the „zero law“. (Cambridge University Press, 1939). (Interestingly, science fiction author Isaac Asimov appropriated the idea of a zero law in his 1985 novel „Robots and Empire (opens in new tab)“ when he realized he had to add a new law to the Three Laws of Robotics (opens in a new window) that replaced the First Law.) How are thermodynamic energy functions measured? It turns out that, as a rule, they cannot be determined either directly or absolutely, and their change can at best be measured in the course of a process. This makes the thermodynamic energy functions somewhat blurred; Only their differences and derivatives are clearly defined. Obviously, the introduction of the ideal gas concept is only an idealization of what can actually be achieved in practice. On a more practical level, for example, volumetric measurements of N2 gas as a function of temperature between +100 and −100 °C could be carried out, while maintaining a constant pressure at 1, 2, 3 bar, etc.
You get a line graph at each pressure, with a slope that increases with pressure.
