Open AccessThe interpretation of the results of Bucherer's experiments on e/m
Author(s) -
Thomas P. Lewis
Publication year - 1925
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1925.0040
Subject(s) - electron , physics , condenser (optics) , electric field , perpendicular , magnetic field , radius , projection (relational algebra) , field (mathematics) , atomic physics , geometry , computational physics , optics , mathematics , quantum mechanics , light source , computer security , algorithm , computer science , pure mathematics
.—In the ‘Physikalische Zeitschrift,’ 9 Jahrgang, No. 22 pp. 755-760, and again, in greater detail, in the 'Annalen der Physik,’ 1909 vol. 28, pp. 513-536, Prof. A. H. Bueherer gives an account of an experiment performed by him with the object of ascertaining which of the various mass formulæ attributed to the electron by theoretical physicists agrees best with experiment. The method is briefly as follows: a source of high speed electrons (a stick of radium fluoride) is fixed on the axis of a circular parallel plate con denser, one of whose plates is connected to earth, and the other to a source o: high potential so as to produce a sensibly uniform electric field in the region between. Perpendicular to the electric field is applied a uniform magnetic field whose effect is to diminish, or increase, the mechanical force on the electron according as the direction of its velocity forms a left-handed or a right-handed system with those of the two fields. Since the distance between the plates is very small compared with their radius, it follows that the velocity of projection of an electron cannot have at arbitrary value if it is to escape from the condenser. Given the direction of projection of an electron, its velocity must lie between two definite limits which depend upon the relative intensities of the two fields, and also upon the distant between the plates of the condenser.