Primary
Electromagnetism ⚪｜Definition｜1st｜20251119205401-00-⌔
Electromagnetism
In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature.1 It is the dominant force in the interactions of atoms and molecules. Electromagnetism describes and relates the three distinct but closely intertwined phenomena of electricity, magnetism, and optics. In, electromagnetism these phenomena are described by the 3 sub-disciplines: electrostatics, magnetostatics, and electrodynamics.
The electromagnetic force is responsible for many chemical and physical phenomena observed in daily life. The electrostatic attraction between atomic nuclei and their electrons holds atoms together. Electric forces also allow different atoms to combine into molecules. Meanwhile, magnetic interactions between the spin and angular momentum magnetic moments of electrons also play a role in chemical reactivity; such relationships are studied in spin chemistry. Electromagnetism also plays several crucial roles in modern technology: electrical energy production, transformation and distribution; light, heat, and sound production and detection; fiber optic and wireless communication; sensors; computation; electrolysis; electroplating; and mechanical motors and actuators.
Electromagnetism has been studied since ancient times to explain the electric phenomena of lightning and static electricity and the magnetic phenomenon of the attraction between magnetized pieces of iron ore and of compasses. In the 18th and 19th centuries scientists developed the mathematical relationships between these phenomena and electric charges and currents. Too they showed that electrical and magnetic phenomena were related and could create a self-sustaining electromagnetic waves which forms visible light and other forms of electromagnetic radiation including Gamma-rays, x-rays, ultraviolet, visible, infrared radiation, microwaves and radio waves.
In the modern era, scientists continue to refine the theory of electromagnetism to account for the effects of modern physics, including quantum mechanics and relativity. The theoretical implications of electromagnetism, particularly the requirement that observations remain consistent when viewed from various moving frames of reference (relativistic electromagnetism) and the establishment of the speed of light based on properties of the medium of propagation (permeability and permittivity), helped inspire Einstein’s theory of special relativity in 1905. Quantum electrodynamics (QED) modifies Maxwell’s equations to be consistent with the quantized nature of matter. In QED, changes in the electromagnetic field are expressed in terms of discrete excitations, particles known as photons, the quanta of light.
Mathematically, electromagnetism is described by electromagnetic fields. These are quantities that describe the electrical (electric field) and magnetic (magnetic field) influence at a given location and time.
Printed 2026-06-28.
(echo:: @ ᯤ)
Link to original Footnotes
Biggs, Ben; published, Jeremy Rehm (23 December 2021). “The four fundamental forces of nature”. Space. ↩
Secondary
• • •