Open AccessThe change of electrical conductivity strong magnetic fields. Part II. —The analysis and the interpretation of the experimental results
Publication year - 1929
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.1929.0073
Subject(s) - disturbance (geology) , field (mathematics) , interpretation (philosophy) , square (algebra) , character (mathematics) , magnetic field , conductor , conductivity , mathematics , electrical resistivity and conductivity , condensed matter physics , physics , pure mathematics , geometry , quantum mechanics , computer science , geology , paleontology , programming language
It is seen from figs. 4 to 31 that all the curves of change of resistance, except for iron and nickel, are exactly similar in character. The increase of the resistance at the beginning is proportional to the square of the magnetic field, but later is directly proportional to the field so that the curve of change of resistance with field is practically a straight line. This change from the square to the linear law takes place gradually after a critical field Hk which for different substances ranges from 5 to 250 kilogauss. The phenomenon is so general that it would seem that it must have a general explanation. The natural explanation would be that when the field is weak, below the critical field (Hk ,), something hinders the appearance of the linear law which is theTrue Law of change of resistance and this law is fully established only when the field is well above the critical value. Our hypothesis to explain this is to assume an initial disturbance which already exists in the metal. Further, we assume that this disturbance is similar to that produced by the outside field and is distributed at random in the conductor. When the outside field is applied, the disturbance which causes the increase of resistance is now the vectorial sum of these two disturbances and the increase of the resistance is proportional to this sum. It is evident that in such a way the general character of the curves will be obtained. When the disturbance produced by the outside field grows larger than that of the inside field, we have the gradual approach to a linear law. To embody these ideas in a quantitative form we assume that the already existing disturbance may be represented by a vectorh , the meaning of which is that a similar disturbance can be produced by a magnetic field pointing in the same direction and having the same magnitude.