Electromagnetic field: Encyclopedia II - Electromagnetic field - Light and electromagnetic waves

Electromagnetic field - Light and electromagnetic waves

Electrically charged particles are constantly emitting (or absorbing) photonic fluid, which is more commonly known as light. So how is light related to electromagnetic waves? Electromagnetic (E-M) waves are the undulatory movements of light, which can always be observed to be emitted by electric charges undergoing acceleration.

If a charged particle is at rest, then it does not emit electromagnetic waves. Instead, it is surrounded by an electrostatic field. If a charged particle is in inertial motion, then the electrostatic field is joined by a magnetostatic field. This pair of static fields produce a movement of electromagnetic energy (i.e. a field of non-zero Poynting vectors), which is similar to an electromagnetic wave, except that the fields are not oscillating.

E-M waves are propagating, expanding, harmonic, oscillating accelerations of the photonic fluid. Since the photonic fluid itself moves at the speed of light (by definition), then E-M waves can move no faster than the speed of light. E-M waves move at a speed close to the speed of light, depending on the medium through which they move (e.g. faster in air than through water, and faster through water than through a glass lens).

Adapted from the Wikipedia article "Light and electromagnetic waves", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki