Affiliations: [a] School of Mechanical Engineering, Tianjin University, Tianjin, China | [b] Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin, China
Abstract: Magnets are widely used in many fields, both industry and our daily life, because of their unique properties such as non-contact interactions and electricity generation. However, behaviors of permanent magnets seem to deviate from our basic understanding that opposite poles attract and like poles repel. We have recently discovered an interesting phenomenon in pairs of permanent magnets with large different sizes where the like poles do not seem to repel and the unlike poles do not seem to attract with each other, due to a localized area with reversed pole existing in the large permanent magnet. In this paper, we first experimentally confirm the existence of this particular phenomenon by studying interactions of several groups of permanent magnets with different sizes, then we introduce the property of the irreversible movements of load line and working point of permanent magnet to figure out this transition process from repulsion to attraction between a pair of permanent magnets with large different sizes. A reasonable explanation is finally given. In the end, we suggest a few applications for this special phenomenon.
Keywords: Magnetic force calculation, load line, demagnetizing field, working point
