a region of space near a magnet, electric current, or moving charged particle in which a magnetic force acts on any other magnet, electric current, or moving charged particle.
a field of force surrounding a permanent magnet or a moving charged particle, in which another permanent magnet or moving charge experiences a force Compare electric field
A magnetic field is said to exist in a region if a force can be exerted on a magnet. If a compass needle is deflected when it is put at a particular location, we say a magnetic field exists at that point, and the strength of the field is measured by the strength of the force of the compass needle. The Earth, the sun, and the Milky Way galaxy all have magnetic fields. All known magnetic fields are caused by the movement of electrical charges. Electrons in orbit in atoms give rise to magnetic fields, so that every atom is, like the Earth, surrounded by a magnetic field. (See magnet and magnetism.)
- Magnetic field of the earth
The magnetic field (see magnetism) that surrounds and permeates the Earth. It is the presence of this field that causes compass needles to line up in a north-south direction. The origin of the Earth’s magnetic field is poorly understood at the present time.
- Magnetic field reversals
Changes in direction or orientation of the magnetic field of the Earth that have occurred from time to time. (Several hundred are known in the geological record.) Sometimes the north magnetic pole is near the geographic North Pole and sometimes near the South Pole in Antarctica. Note: The causes of these reversals are not known […]
noun 1. . noun, Electricity. 1. that part of the magnetic induction that is determined at any point in space by the current density and displacement current at that point independently of the magnetic or other physical properties of the surrounding medium. Symbol: H. magnetic field strength A vector quantity indicating the ability of a […]
noun, Electricity. 1. the total magnetic induction crossing a surface, equal to the integral of the component of magnetic induction perpendicular to the surface over the surface: usually measured in webers or maxwells. noun 1. a measure of the strength of a magnetic field over a given area perpendicular to it, equal to the product […]