elektromagnetisme

Elektromagnetisme is a branch of physics that studies the interactions between electric charges, currents, and magnetic fields. It covers the generation, transmission, and reception of electromagnetic waves and explains how electricity and magnetism influence each other.

Historically, electric and magnetic phenomena were investigated separately until experiments by Ørsted, Faraday, and Ampère indicated a deep connection. In the 1860s James Clerk Maxwell formulated a set of equations unifying electricity, magnetism, and light, showing that changing electric and magnetic fields propagate as waves at the speed of light.

Key concepts include electric fields, magnetic fields, and the Lorentz force that governs how charges move in fields. Maxwell's equations describe Gauss's laws for electricity and magnetism, Faraday's law of induction, and the Ampère-Maxwell law with displacement current. They predict electromagnetic waves that span a broad spectrum from radio to gamma rays and propagate through vacuum and matter.

Electromagnetism underpins many technologies: electric machines such as motors and generators, transformers, wireless communication, radio, television, radar, optics, and medical imaging like magnetic resonance imaging (MRI), which relies on magnetic fields and radiofrequency pulses.

In modern physics, electromagnetism is described by quantum electrodynamics, where interactions are mediated by photons. The theory is compatible with special relativity and provides one of the most precisely tested frameworks in science, with wide-ranging implications for both fundamental physics and engineering.