A STUDY ON THE ATTRACTION OF ELECTROMAGNET

Abstract

The electromagnet is the best teaching material, in order to make children study the magnetism with the electricity. According to the contents of the course of study in sixth grade of elementary school (1978), the strength of electromagnet, that is the magnetic attraction, is studied qualitatively. But the mutual relation of things and phenomena of nature will be more clear by means of quantitative investigation than qualitative. In order to handle quantitatively the attraction of electromagnet in a curriculum of school, the law or the expression should be used. Then the author has verified whether its theoretical expression, F: attraction of electromagnet B: magnetic flux density φ: magnetic flux, S: contact area μ₀: magnetic permeability of vacuum hold good or not at experiment. As the results, it was proved that the above expression hold good atU-form electromagnet on condition that there is no gap at the contact surface so that the magnetic flux density is equal there.