The propagation of an electromagnetic wave in free space, such as in a vacuum, can be described by Maxwell's equations. These equations form the foundation of classical electromagnetism and govern the behavior of electric and magnetic fields.
The process of electromagnetic wave propagation involves the following steps:
Generation of an electromagnetic wave: An electromagnetic wave is typically generated by an oscillating charged particle or an accelerating charged particle. This generates oscillating electric and magnetic fields that are mutually perpendicular to each other and propagate away from the source.
Formation of a changing electric field: The oscillating charged particle creates a changing electric field. As the electric field changes, it induces a magnetic field perpendicular to it according to one of Maxwell's equations.
Formation of a changing magnetic field: The changing magnetic field, in turn, induces a changing electric field according to another of Maxwell's equations. This mutual induction between the electric and magnetic fields enables the wave to propagate.
Self-sustaining wave propagation: The changing electric and magnetic fields sustain each other as they propagate through space. The wave consists of oscillating electric and magnetic field components that are orthogonal to the direction of propagation.
Speed of light: Electromagnetic waves in free space travel at the speed of light, denoted by "c," which is approximately 299,792 kilometers per second (or about 186,282 miles per second) in a vacuum.
Transverse nature: Electromagnetic waves are transverse waves, meaning that the oscillations of the electric and magnetic fields occur perpendicular to the direction of wave propagation. This characteristic allows for the wave to propagate through space without requiring a medium.
Throughout the process of propagation, the energy carried by the electromagnetic wave is continuously transported without the need for a physical medium. This fundamental understanding of electromagnetic wave propagation laid the groundwork for the development of technologies such as radio, television, wireless communication, and many other applications of electromagnetism.