# What is electromagnetism?

Electromagnetism is a branch of physics that studies the interaction between particles with electric and magnetic fields.

Most of the forces in the known world have to do with electromagnetism, such as light.

## What are Maxwell’s equations?

These equations thoroughly describe electromagnetic phenomena, unifying light, electricity, and magnetism for the first time as the same phenomenon with different manifestations. The equations were devised in 1865 by Scottish mathematician and scientist James Clerk Maxwell, and they summarize the works of numerous scientists who preceded him, including Ampere, Gauss, Sturgeon, Henry, Faraday, Ohm, and Coulomb, among others.

It was originally 20 equations, but in 1884, O. Heaviside and W. Gibbs grouped them into four and turned them into vector differential equations. This synthesis left out a term, however, that is fundamental for the study of electromagnetism. That term is the well-known Lorentz Force. The Lorentz force and Maxwell’s equations are sufficient to describe and study any electromagnetic phenomenon.

Maxwell’s equations are considered to be the second point of great unification in physics (the first was the creation of Newtonian physics). Thanks to these equations, the subsequent works of Albert Einstein, Nikola Tesla, and Thomas Alva Edison were possible.

## Since when has electromagnetism been a known force?

Electromagnetism has been known and intuited since ancient times; it was observed in some meteorological phenomena like thunderstorms. However, there was not enough knowledge about electricity to be able to truly understand it at that time.

It wasn’t until 1820 that Danish physicist Hans Christian Ørsted conducted an experiment that allowed him to discover and demonstrate the relationship between electricity and magnetism.

## What are the branches of study under electromagneticism?

The study of electromagnetism is fundamentally divided into two branches:

1. Electrostatic: studies the phenomena that have to do with charged bodies that are at a state of rest, that is, the phenomena related to the intrinsic charge of matter when not dependent on time.
2. Electrodynamics: studies the phenomena that have to do with charged bodies in motion, as well as variable magnetic and electric fields. It, in turn, is divided into:
1. Classical electrodynamics
2. Relativistic electrodynamics (when a reference system is used)

However, they are also branches of electromagnetism:

1. Magnetostatics: studies the phenomena associated with magnetic fields that are constant over time.
2. Quantum electrodynamics: initially, electromagnetism was a macroscopic branch of physics, meaning it applied to large quantities of particles, not to phenomena occurring in atoms or molecules. However, at the beginning of the 20th century, the first quantum revolution took place. This forced scientists to develop a quantum theory that was applicable to electromagnetics, thus giving rise to quantum electrodynamics, which could also be understood as quantum field theory.