Magnets are mainly divided into two categories: permanent magnets and electromagnets. Natural lodestones are the earliest permanent magnetic materials utilized by humans. Artificially manufactured permanent magnets such as NdFeB and ferrite magnets feature long-lasting and stable magnetism, making them the most widely used magnets in daily scenarios. Electromagnets generate magnetic force only when powered on and lose magnetism once the power is cut off. Their magnetic strength is freely adjustable, so they are commonly applied in automated equipment.
Magnets have specific usage limitations. Long-term exposure to high temperatures or violent impact will disrupt their internal magnetic domain structure, resulting in reduced magnetic force or even complete demagnetization. As early as ancient times, humans created the south-pointing chariot and compass with natural lodestones to identify directions for navigation and travel.
Today, magnets have a broader range of applications. Permanent magnets are essential for refrigerator magnetic stickers, Bluetooth earphones, electric fan motors and magnetic door locks. Industrial cranes, electromagnetic valves and relays rely on electromagnets to operate normally. In high-end fields, high-performance magnets serve as core components for MRI scanners, maglev equipment, new energy vehicle motors and wind turbines. Small and unassuming as magnets seem, they are indispensable key materials that support modern life and industrial technological development.