Updated at 23 Jun 2026
Natural magnetic fields, such as Earth's magnetic field caused by geologic charge flows, and technologically generated fields via electric currents are discussed. Conductors shaped into loops or coils produce strong magnetic fields, with high-frequency fields classified under RF radiation.
The Earth's magnetic field is caused by the continuous “geological” flow of charge within the Earth. The field strength, or flux density, is 40–60 µT. The magnetic field of a bar magnet is generated by the intrinsic motion of electrons within the metal atoms. In this process, groups of atoms are arranged in such a way that their individual magnetic fields combine to form a kind of micromagnet.
