Some metals naturally attract other metals with a force known as magnetism. Even before electricity was understood, scientists crafted compasses from tiny strips of naturally occurring magnets that pivot to align with Earth's magnetic field, pointing north because the field runs from south to north.
When two metals attract across space, one or both are likely magnetic. Permanent magnets—usually containing iron—exhibit the strongest natural magnetism, a phenomenon called ferromagnetism. Earth's magnetic field is generated by the motion of its molten nickel‑iron core and becomes visible when charged particles from the Sun collide with our atmosphere near the magnetic poles, producing the aurora borealis.
Every atom’s nucleus of protons and neutrons is orbited by electrons, which carry a negative charge. The arrangement of these electrons gives atoms a directional orientation, and their orbital motion creates a weak magnetic field. Whenever an electrical current flows—especially in a circular or spiral path—a magnetic field emerges. Electromagnets harness this principle, allowing their magnetism to be switched on and off with the current.
Metals whose electronic structures allow their electrons to align more easily form stronger magnetic fields. Iron, nickel, cobalt, and gadolinium are the most readily magnetized. While aluminum and copper can exhibit magnetic behavior, the fields they generate are weak. Oxides and alloys containing iron—such as rust and steel—also magnetize readily, and the greater the number of alignable electrons, the stronger the magnet.
Magnetite, an iron oxide found in nature, often displays a strong magnetic field and is commonly known as a lodestone. Modern research suggests that lightning strikes may have magnetized these lodestones. Magnetite’s crystalline structure allows large groups of molecules, called domains, to align in the same direction, producing a potent magnetic field. Other minerals can acquire weak magnetism from Earth's magnetic field, and studying ocean trench rocks reveals how the planet’s magnetic poles have flipped over millennia.
Creating a simple electromagnet is straightforward: wrap many coils of copper wire around a steel bar or nail, connect a small battery, and pass current through the coil. The metal will become magnetic, retaining some magnetism even after the current stops and the wire is removed. Resources provide step‑by‑step instructions.
