Difference between revisions of "Magnetism"

Latest revision as of 08:14, 9 May 2016

Magnetism is a class of physical phenomena that are mediated by magnetic fields.

Description

Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments.

Every material is influenced to some extent by a magnetic field.

The most familiar effect is on permanent magnets, which have persistent magnetic moments caused by ferromagnetism.

The prefix ferro- refers to iron, because permanent magnetism was first observed in a form of natural iron ore called magnetite, Fe3O4.

Most materials do not have permanent moments. Some are attracted to a magnetic field (paramagnetism); others are repulsed by a magnetic field (diamagnetism); others have a more complex relationship with an applied magnetic field (spin glass behavior and antiferromagnetism).

Substances that are negligibly affected by magnetic fields are known as non-magnetic substances. These include copper, aluminium, gases, and plastic. Pure oxygen exhibits magnetic properties when cooled to a liquid state.

The magnetic state (or magnetic phase) of a material depends on temperature and other variables such as pressure and the applied magnetic field. A material may exhibit more than one form of magnetism as these variables change.

See also

• Coercivity
• Gravitomagnetism
• Magnetic hysteresis
• Magnetar
• Magnetic bearing
• Magnetic circuit
• Magnetic cooling
• Magnetic field viewing film
• Magnetic stirrer
• Magnetic structure
• Magnetism and temperature
• Micromagnetism
• Neodymium magnet
• Physics
• Plastic magnet
• Rare-earth magnet
• Spin wave
• Spontaneous magnetization
• Vibrating sample magnetometer

External links

• Magnetism @ Wikipedia