What is the difference between the magnetism of a magnet and its surface magnetism?

Many people talk about the magnetism of a magnet and its surface magnetism. Specifically, what are the concepts of magnetism and surface magnetism of a magnet, and how are they defined? What are the relationships and influences between the two?

First, the definition of surface magnetism: Surface magnetism refers to the magnetic induction intensity on the surface of a magnet. The surface data presented on the surface of a magnet is only a data reflection of the magnet itself on the measuring tool. Since the induction of each measuring tool is not necessarily accurate, there is no definite specification for the surface magnetism of magnetic products. The most common method is to enlarge the tolerance range of the data or directly make requirements based on the product itself. After all, the data is only an observable performance.

Generally, the measuring tools for measuring the surface magnetism of a magnet use a Gauss meter, also called a Tesla meter. However, since there is no specific standard for the products produced by each manufacturer, and because the Hall induction elements on the Gaussmeter are different, the Hall induction strength is different, and the measured surface magnetism is also different. In the simplest terms, for the same product, if we use a domestic Gaussmeter to measure, if the measured surface magnetism is 3000GS, and if we use a Japanese Gaussmeter to measure, because of the quality problem of the Hall induction element on the Gaussmeter, the surface magnetism measured by the Japanese Gaussmeter is about 200GS higher. Therefore, if you only look at the surface magnetism of a product, you cannot judge whether the magnet product is good or bad.

And the magnetism we are talking about usually refers to the property that can attract iron, cobalt, nickel and other materials.