Fluctuating Fields:

The fluctuating current in a wire or a variable charge gradient among two close objects gives increase to a magnetic field and an electrical field in grouping. Such fields leapfrog however space therefore the EM field can travel long distances with less attenuation than either an electrical field or a magnetic field only. The magnetic and electrical fields in such circumstances are perpendicular to each other all over in space. The direction of travel of the resultant EM field is perpendicular to both the magnetic and electrical lines of flux, which is as shown in figure below.

Figure: An EM wave is consists of fluctuating, equally perpendicular magnetic & electrical lines of flux. The field travels at right angles to both sets of flux lines.

In order for an EM field to subsist, the electrons in a wire or the other conductor not only should be set in motion, though they also should be accelerated. That is, their velocity should be made to change. The most general technique of creating this kind of circumstances is the introduction of an alternating current (ac) in an electrical conductor. It can also outcome from the bending of charged-particle beams by magnetic or electrical fields.