By John Papiewski | Updated March 24, 2022
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Magnets fall into two main categories: permanent and electromagnets. A permanent magnet retains its magnetic field indefinitely—think of a refrigerator magnet that stays in place for years. An electromagnet, on the other hand, generates a magnetic field only when electric current flows through its coil.
One of the biggest advantages of an electromagnet is its tunability. With no current, the coil produces no field. A small current yields a weak field, while a larger current amplifies the force, enabling the device to lift or pull heavier objects. This on‑off capability makes electromagnets indispensable in applications ranging from household gadgets to massive industrial cranes.
Permanent magnets are limited by the materials they’re made from. The strongest commercially available permanent magnets combine iron with neodymium. Even these impressive alloys are eclipsed by the best electromagnets, which can be more than 20 times stronger when driven with adequate current.
Electromagnets are ubiquitous in modern technology. Small units power electronic locks on cars and apartment doors. Scrapyard cranes use powerful electromagnets to lift entire vehicle bodies. Medical imaging devices, such as MRI scanners, rely on high‑field electromagnets to produce detailed internal images. In research, the most powerful electromagnets probe the fundamental properties of matter.
Permanent magnets find use in everyday items: toys, handheld devices like electric razors, and clasps for jewelry. Larger units drive household appliances, speakers, and the electric motors in hybrid vehicles, where strong, reliable magnetic fields are essential.
