电磁现象在自然界中极为普遍,它涉及到非常广泛的领域。人类很早就知道摩擦过的琥珀能吸引轻小物体。后来,人们发现有很多物质都能由于相互摩擦而带电,并且带电物体之间存在着相互排斥或相互吸引的作用。法拉第发现电磁感应定律和电流的磁效应为制造更加有效的电源和动力机提供了科学依据,展现了电磁现象的规律在技术上可以获得重要应用的崭新前景。 Electromagnetic phenomena are extremely common in nature and involve a very wide range of fields. Humans have long known that rubbed amber can attract light objects. Later, it was found that many substances can be charged with each other due to mutual friction, and charged objects exist mutually exclusive or mutual attraction. Faraday found that the electromagnetic induction law and the magnetic effect of current provide a scientific basis for the manufacture of more efficient power and power machines, demonstrating a new prospect of technically important applications for the law of electromagnetic phenomena.