ELECTRIC CHARGE CARRIERS IN MOTION

Whenever the atoms in a ferromagnetic material are aligned, a magnetic field exists. A magnetic field also can be caused by the motion of electric charge carriers either in a wire or in free space.
The magnetic field around a permanent magnet arises from the same cause as the field around a wire that carries an electric current. The responsible factor in either case is the motion of electrically charged particles. In a wire, the electrons move along the conductor, being passed from atom to atom. In a permanent magnet, the movement of orbiting electrons occurs in such a manner that an “effective current” is produced by the way the electrons move within individual atoms.
Magnetic fields can be produced by the motion of charged particles through space. The Sun is constantly ejecting protons and helium nuclei. These particles carry a positive electric charge. Because of this, they produce “effective currents” as they travel through space. These currents in turn generate magnetic fields. When these fields interact with the Earth’s geomagnetic field, the particles are forced to change direction, and they are accelerated toward the geomagnetic poles.
If there is an eruption on the Sun called a solar flare, the Sun ejects more charged particles than normal. When these arrive at the Earth’s geomagnetic poles, their magnetic fields, collectively working together, can disrupt the Earth’s geomagnetic field. Then there is a geomagnetic storm. Such an event causes changes in the Earth’s ionosphere, affecting long-distance radio communications at certain frequencies. If the fluctuations are intense enough, even wire communications and electrical power transmission can be interfered with. Microwave transmissions generally are immune to the effects of geomagnetic storms. Fiberoptic cable links and free-space laser communications are not affected. Aurora (northern or southern lights) are frequently observed at night during geomagnetic storms.

مواضيع ذات صلة

عجائب المجالات المغناطيسية

المجال المغناطيسي الارضي

Planetary magnetism

Therapy and treatment

Cellular biology

Magnetotaxis

Magnetic field effects

Electrodeposition

Magnetic memory

Materials for spin electronics

Actuators

Sensors