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Title: The complete photo-electric emission from potassium
Author: Butterworth, J.
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1929
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This thesis is in two parts, the first portion of which describes experiments which were carried out to detect a positive photo-electric emission from potassium. The result of these was that if such an emission occurs it is of the order of 10 times the negative emission at most, i.e. a thousand times as small as the value found by Dember, who claimed to have definite evidence Of a photo-electric effect. The major portion concerns the two or wore threshold frequencies of potassium. A brief historical account is given ending with the work of Richardson and Young in which they predict for the sensitised potassium surface a threshold at 10,000 AU and another at 30,000 AU. Precautions were taken to obtain a clean surface in a high vacuum, the apparatus being of a form which made the saturation of the photo-electric currents easy and the potassium was subjected to approximately black body radiation. Using Richardson's formula for the saturated currents, the work functions, b, and the corresponding threshold frequencies were determined. The values of the frequencies found were 7,100 A.U., 10,000 A.U. 21,000 A.U. A tentative explanation is given of certain Hysteresis phenomena which were observed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Atomic Physics