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The quantum principles used in atomic clocks are examined.
Metadata describing this Open University video programme
Module code and title: SM351, Quantum theory and atomic structure
Item code: SM351; 08
First transmission date: 05-08-1974
Published: 1974
Rights Statement:
Restrictions on use:
Duration: 00:23:06
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Producer: Andrew Millington
Contributors: Paul Clark; Allan Krass
Publisher: BBC Open University
Keyword(s): Aircraft collisions; Ammonia clock; Atomic clock; Caesium clocks; Crystal oscillator; Molecular beam apparatus; Quantum principles
Footage description: Paul Clark introduces the programme. He explains why atomic clocks are used as time standards by such bodies as the BBC. Clark explains why a precision time standard is needed to correlate all clocks. He then uses a schematic diagram of a general clock to point out the principal parts found in any clock. Allan Krass with an early ammonia atomic clock. He briefly points out various components. Krass uses a ball and stick model of an ammonia molecule to examine the way in which quantum mechanics explains the oscillating motion of the molecule. Krass shows, with the aid of graphics, how the splitting of energy levels, when two harmonic oscillator wells are brought together, is related to the energy states in the ammonia molecule. Some computer animations are used to show the relation between energy level and wave functions. Paul Clark, with a diagram of a molecular beam apparatus, describes how it works. He shows how the transistor in ammonia is used to control the frequency of a crystal oscillator which in turn provides the period for the atomic clock. Several animations are also used. Paul Clark compares the accuracy of the ammonia standard with that of the caesium standard. He then points out some of the practical applications for this measure of accuracy. Shots of a caesium clock on board an aircraft and in the studio. Paul Clark sums up.
Master spool number: 6HT/71433
Production number: 00525_1145
Videofinder number: 1048
Available to public: no