Electromagnetic field

From The Book of THoTH (Leaves of Wisdom)

The electromagnetic field is a physical influence (a field) that permeates through all of space and which arises from charged objects and describes one of the four fundamental forces of nature - electromagnetism. It can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by non-moving charges and the magnetic field by moving charges (currents); these two are often described as the sources of the field. As velocities are observer-dependent, so is the distinction between electric and magnetic field. The way in which charges and currents interact with the electromagnetic field is dictated by Maxwell's equations and the Lorentz Force Law.

Nature of the electromagnetic field

As with many physical concepts, there are various ways of thinking about the electromagnetic field. The field may be viewed in two distinct ways.

Continuous structure

Oscillating electric and magnetic fields may be viewed in a 'smooth', continuous, wavelike manner. These fields are sometimes assumed to vary sinusoidally with a single frequency. In this case, energy is viewed as being transferred continuously through the electromagnetic field between any two locations. For example, the metal atoms in a radio transmitter appear to transfer energy continuously. This view is useful to a certain extent (radiation of low frequency), but problems are found at high frequencies (see ultraviolet catastrophe). This problem leads to another view.

--Angel 08:37, 16 May 2006 (CDT)