Investigating magnetization of permanent magnets by magnetic flux viewing film

Abstract

Permanent magnets are used in many current industrial as well as home appliances today. Frequently, kitchen plastic magnets could be found at the refrigerators at home. However, the magnetic domain structure of such permanent plastic foils is not known and understood to the users at all. The purpose of this paper is to explain the magnetic domain structure of plastic magnets with Halbach array and ferrite or neodymium magnet polarization orientation. Principles of magnetic field visualization foils (magnetic flux detector and colour changing viewing film) is explained and demonstrated on multipole magnetic structures. Experiments with magnetic polarization reversal by the strong neodymium magnet in weaker ferrite magnetic material is demonstrated. All presented principles are collected in the simple magnetic set and suggested for education of school children of different ages. Elementary school children below 10 years age are mostly interested only in making hidden pictures in magnetic paper and ferrite magnet. Older school children of 11–12 years are able to absorb more knowledge about behaviour and properties of magnets.