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Some basic experiments on magnetism are performed in the studio, particulaurly those demonstrating the relationship of magnetism to circualating electric currents. Parts of the programme are filmed... in Iceland and these apply the basic ideas above to an examination of the record of earth's magnetic field as found in rock's.
Metadata describing this Open University video programme
Module code and title: S101, Science: a foundation course
Item code: S101; 05
First transmission date: 20-03-1979
Published: 1979
Rights Statement:
Restrictions on use:
Duration: 00:24:00
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Producer: Patricia McCurry
Contributors: Geoff Brown; Mike Pentz; Leo Kristjansson
Publisher: BBC Open University
Keyword(s): Continental drift; Magnetism
Footage description: Geoff Brown, sitting on a rock somewhere in Iceland, explains the difference between magnetic and geographic north. He draws on a pad of paper as he talks. Brown goes on to examine the magnetic properties of some rock samples which he hammers out of the basalt outcrop. He points out the similarity of the rock samples to a bar magnet. Mike Pentz, in the studio, performs some basic experiments on magnetism. He begins by demonstrating that a compass needle can be made to deflect by a current in a conductor and that a current carrying conductor can be made to deflect by a bar magnet. Pentz goes on with his demonstration. He shows that two currents carrying conductors will be either attracted or repelled depending on the direction of the currents. The next demonstration shows compass needles lining up in a circle around a perpendicular conductor. The effect of a circulating current (a conductor in the shape of a coil) on the production of a magnetic field is demonstrated. Pentz goes on to demonstrate that when magnetic materials, in a magnetic field, cool below their Curie temperatures, they acquire a magnetic field in the direction of the field they were exposed to at the time of cooling. Film shots of a volcanic eruption. Shots of an Icelandic landscape with close-ups of solidified lava flows. Geoff Brown explains how the direction of the earth's magnetic field, at the time the lavas cooled, came to be recorded in the rocks. Film shots of Leo Kristjannsson drilling rock cores in Iceland and of him analysing these for magnetic direction in the laboratory. Commentary by Geoff Brown explains how this is done and how the data is plotted. Shots of a north polar projection of the earth showing the location of the magnetic pole at various times. A computer animation showing the earth's alternating magnetic fields and shots of an epoch chart which shows the direction of the magnetic field during several epochs of the earth's history. Commentary by Geoff Brown sums up the programme.
Master spool number: 6HT/72961
Production number: FOUS005W
Videofinder number: 1180
Available to public: no