Why are transformer cores made from thin layers of iron?

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Learn about magnetic fields and the levels of particles, atoms, crystals, and domains — magnet Magnetic fields and the levels of magnetism of particles, atoms, crystals, and domains.

Transformer cores are constructed from thin, insulated layers of iron—a process known as lamination—to minimize the formation of eddy currents.12

These eddy currents are circulatory electrical currents induced within the metal core by the changing magnetic field generated by the alternating current in the coils. If the core were a solid block of iron, these currents would flow freely, resulting in significant energy loss in the form of unwanted heat. By using thin, isolated sheets, the path for these currents is restricted, which improves the overall efficiency of the transformer.12

Additionally, transformer cores are typically made from materials with narrow hysteresis loops to further reduce energy waste caused by the continuous reversal of the material's magnetization.3