the.com/magnetic field
Invisible rules a moving charge writes for every other charge to obey.
means The region around a magnet or electric current where its magnetic force can be detected and acts on other magnets or moving charges.
from 'Magnetic' traces to Magnesia, a region in ancient Greece (and Asia Minor) associated with naturally magnetic lodestone — the Greeks called it 'ho Magnes lithos,' the 'Magnesian stone.' 'Field,' in the physics sense, is an 18th-19th century extension of the everyday word for open land — scientists like Faraday borrowed it to describe a space permeated by invisible force, as if the force itself cultivated the ground around it.
- source
- only ever made by moving charge, never charge alone
- monopoles
- never found; every magnet ships with two poles
- earth's own
- generated by churning liquid iron, flips every few hundred thousand years
- field lines
- always close loops, no beginning, no end