An Experiment on Electromagnetic Induction and Relative Motion

Publisher Website
Google Scholar
Abstract
Electromagnetic Induction; Charging Effect of the Rotation of an Iron Sphere in a Uniform Magnetic Field.—The electromagnetic theory of this effect among others was developed by the author in a former paper. The answer which the theory gives is perfectly definite, but the nature of the problem is such that one who is accustomed to think in terms of moving lines of force may be uncertain as to the proper basis of attack and may even, quite plausibly, arrive at a result one third as great as it should be. Therefore an experimental verification of the theoretical formula seemed worth while carrying out. It was found that when an iron sphere with a radius of 3.17 cm. was rotated at rates ranging from 3,250 to 6,430 r.p.m., in a magnetic field ranging from 3,930 to 6,070 gauss, the changes of potential of an insulated copper shell surrounding the iron sphere, which were observed when the magnetic field was reversed ranged from 0.0114 to 0.0359 volt, while the corresponding calculated values ranged from 0.0116 to 0.0353 volt. In view of the experimental difficulties the fact that the average difference between observed and calculated changes of potentials for the seventeen sets of readings is only 1.7 per cent. is considered a satisfactory verification of the theory.

This publication has 0 references indexed in Scilit: