Available online
Description
The programme underlines the main characteristics of phase transitions and also tries to demonstrate how phase changes of higher order are studied experimentally.
The programme underlines the main characteristics of phase transitions and also tries to demonstrate how phase changes of higher order are studied experimentally.
| Module code and title: | ST285, "Solids, liquids and gases" |
|---|---|
| Item code: | ST285; 15 |
| First transmission date: | 15-09-1973 |
| Published: | 1973 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:30 |
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| Producer: | Andrew Millington |
| Contributors: | Barrie Jones; Milo Shott; Steve Swithenby; Mike Wells |
| Publisher: | BBC Open University |
| Keyword(s): | Entropy change; First and higher order; Phase changes; Specific heat curve |
| Footage description: | Film shots of boiling kettle and freezing of nitrogen in a test tube. Milo Shott introduces the programme. Barrie Jones with a simple thermodynamic system in which pressure and temperature are kept constant but volume is increased as energy is input. He concludes that a first order phase transition is taking place. Milo Shott with a PVT surface which represents equilibrium states for a system containing one pure substance. He uses this to explain the phase change shown in the experiment above. Barrie Jones with the experiment again (a boiling water system). He explains what was happening. Jones then uses the apparatus for an experiment to determine the entropy of changing 1 gram of water from the liquid to the gaseous state. He demonstrates the method on a drawing board. Milo Shott with a PVT surface for water whose entropy is a function of pressure and temperature. He describes the main features of this surface. Shott next briefly summarises the features of first order transitions. These are captioned. Milo Shott explains how higher order transitions differ from first order transitions. Film shots of an experiment at Clarendon Laboratory, Oxford to investigate interaction in ordered magnetic systems for which a measurement of specific heat in the range 0.5 degrees to 20 degrees K is necessary. Specific heat changes abruptly at the magnetic phase transition. Michael Wells examines and explains the central apparatus for the experiment, a cryostat, with the aid of animated diagrams. Michael Wells then points out the rest of the apparatus and explains how it works. He uses a diagram as visual aid. Wells and Stephen Swithenby deduce the specific heat curve for terbium aluminate. A chart recorder records the data. Milo Shott summarises the main distinctions between first and all higher order transitions. He uses a graphics board to emphasise this point. |
| Master spool number: | 6HT/71053 |
| Production number: | 00525_1039 |
| Videofinder number: | 692 |
| Available to public: | no |
