"Magnetic Field"

"Magnetic Field"

• In physics, a magnetic field is a field that permeates space and which exerts a magnetic force on moving electric charges and magnetic dipoles. Magnetic fields surround electric currents, magnetic dipoles, and changing electric fields.
  When placed in a magnetic field, magnetic dipoles align their axes to be parallel with the magnetic field, as can be seen when iron filings are in the presence of a magnet (see picture at right). Magnetic fields also have their own energy and momentum, with an energy density proportional to the square of the field intensity. The magnetic field is typically measured in either teslas (SI units) or gauss (cgs units).
  There are some notable specific incarnations of the magnetic field. For the physics of magnetic materials, see magnetism and magnet, and more specifically ferromagnetism, paramagnetism, and diamagnetism. For constant magnetic fields, such as are generated by stationary dipoles and steady currents, see magnetostatics. For magnetic fields created by changing electric fields, see electromagnetism.
  The electric field and the magnetic field are closely interlinked due to Einstein's theory of special relativity (see relativistic electromagnetism). Together, they make up the electromagnetic field.