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Using as examples a small hydro-electric power station in North Wales and a controlled experiment with an electric kettle, the programme illustrates the principle of conservation of energy by measu...ring and balancing all major inputs and outputs.
Metadata describing this Open University video programme
Module code and title: S101, Science: a foundation course
Item code: S101; 08
First transmission date: 24-04-1979
Published: 1979
Rights Statement:
Restrictions on use:
Duration: 00:24:00
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Producer: John Stratford
Contributors: Stuart Freake; Mike Pentz; Graham Farmelo
Publisher: BBC Open University
Keyword(s): Hydro electric power
Footage description: Shots of a lake in North Wales. Stuart Freake standing on the shore introduces the programme. He points out that there is a considerable amount of gravitational energy stored in this lake. Freake calculates the amount of gravitational energy one would theoretically expect to be converted to some other form if one kilogram of water were taken from the lake to the valley below. Film of Mike Pentz inside the hydro-electric power station in the valley below the lake. He points out various pieces of equipment. Pentz goes on to take readings of electrical output from the three generators in the station and from the flow meter which indicates the rate of flow of water through the station. Mike Pentz and Stuart Freake, outside the power station, work out the amount of gravitational energy actually being converted to electricity Pentz uses these figures to make an energy balance sheet and speculates that heat generation accounts for the difference between theoretical and actual output. To determine if heat generation is indeed responsible for the output discrepancy, Pentz, Graham Farmelo, and Stuart Freake take measurements of the water at the lake and in valley after it has passed through the turbines. They calculate the amount of heat which has generated and add this to the energy balance sheet. Stuart Freake sums up the above experiment. A similar experiment, but one done under laboratory conditions, takes up the rest of the programme. Stuart Freake outlines the experiment and points out the equipment to be used - an insulated electric kettle containing a known amount of water, a domestic electricity meter, and a thermometer. Mike Pentz sets out the physics and mathematics for this experiment. He writes on a large pad as he talks. Stuart Freake takes the input and output readings and Pentz tries to apply them to his equation. The experiment cannot be carried through because the mass of the kettle and its specific heat are not known. Freake outlines a method which will get around the lack of data on the kettle and starts the experiment again. Pentz sets out the equation for this modified experiment. Stuart Freake takes the readings for the modified experiment and Pentz slots the data into his equation. He then solves the equation and examines the result. Students are asked to apply the estimates for experimental error published in the broadcast notes to the results before deciding if the Principle of Conservation of Energy has been upheld.
Master spool number: 6HT/72977
Production number: FOUS008D
Videofinder number: 1183
Available to public: no