electromagnetica

Electromagnetica, or electromagnetism, is the branch of physics that studies the electromagnetic force, which arises from electric charges and currents and is mediated by electric and magnetic fields. The essential framework is given by Maxwell's equations, which describe how E and B fields propagate, interact with matter, and give rise to electromagnetic waves that travel through space at the speed of light in vacuum.

Historically, ideas about electricity and magnetism emerged in the 17th through 19th centuries, leading to Coulomb's law, Ampère's law, and Faraday's law of induction. James Clerk Maxwell unified these phenomena in a set of equations in the 1860s, predicting that changing electric and magnetic fields generate waves. Heinrich Hertz experimentally confirmed the existence of radio waves, establishing a practical foundation for modern communications.

In classical electromagnetism, electric field E exerts a force on charges; magnetic field B influences moving charges via the Lorentz force F = q(E + v×B). Electromagnetic waves, solutions to Maxwell's equations, include visible light and radio waves and are characterized by frequency, wavelength, polarization, and intensity. Energy flow is described by the Poynting vector S = E×H.

Maxwell's equations also set the stage for quantum descriptions, with quantum electrodynamics providing a quantum field theory of light and its interactions. In practical terms, electromagnetism underpins electrical power generation and distribution, electric motors and transformers, wireless and optical communications, imaging, and many technologies.

Key constants include the speed of light c, and material properties such as permittivity and permeability of media. The theory assumes special relativity and is formulated in various unit systems; in modern practice SI units are standard.