What is a Magnet?

Summary

Key Points

• —Magnets were first discovered as naturally occurring minerals in ancient Greece, named after the region of Magnesia, which were found to attract iron and either attract or repel each other. 0:23
• —Unmagnetized iron consists of randomly oriented tiny crystal magnets called domains, while magnetized iron has all these domains aligned, giving it a distinct north and south side. 0:48
• —During magnetization, these domains suddenly flip into alignment, a process that can be made audible, as demonstrated with nickel in a coil. 1:20
• —Magnetism in materials like iron can be destroyed by heating, which disrupts the alignment of the magnetic domains. 2:29
• —Besides iron, cobalt and nickel are also magnetic, and their proximity on the periodic table suggests that magnetism is fundamentally a result of electron valence. 2:33
• —Early theories, including an experiment by Albert Einstein and Wander de Haas, incorrectly hypothesized that orbiting electrons were the cause of magnetism. 3:15
• —It was later discovered that electrons possess a property called "spin," and the alignment of these electron spins is what ultimately results in the magnetic properties of materials. 3:34
• —This natural alignment of electron spins, particularly a pair of valence electrons with aligned spins, is most prevalent in iron, nickel, and cobalt, representing a quantum mechanical effect observable in everyday life. 4:05