electromagnetism

Introduction
Fundamentals
- Coulomb’s law
- Principle of charge conservation
- Electric fields and forces
- Magnetic fields and forces
- Interaction of a magnetic field with a charge
Effects of varying magnetic fields
- Faraday’s law of induction
- Self-inductance and mutual inductance
Effects of varying electric fields
Historical survey
- Early observations and applications
- Emergence of the modern sciences of electricity and magnetism
  - Pioneering efforts
  - Invention of the Leyden jar
  - Formulation of the quantitative laws of electrostatics and magnetostatics
- Foundations of electrochemistry and electrodynamics
  - Development of the battery
  - Experimental and theoretical studies of electromagnetic phenomena
    - Faraday’s discovery of electric induction
    - Maxwell’s unified theory of electromagnetism
  - Discovery of the electron and its ramifications
  - Special theory of relativity
- Development of electromagnetic technology

References & Edit History Quick Facts & Related Topics

Images & Videos

Understand how the concept of touch changes with the presence of electrons between two objects

Two diagrams compare electric fields: on the left, arrows radiate outward from a red sphere with a plus sign, showing the field of a positive charge; on the right, arrows point inward toward a blue sphere with a minus sign, showing the field of a negative charge.

Two diagrams show the magnetic field around a long straight wire carrying current. Panel A presents an end view with concentric circular field lines around the wire, current flowing toward the viewer. Panel B shows a three-dimensional view with the wire angled across the image and circular magnetic field lines surrounding it.

Diagram showing the magnetic force on moving charges: positive and negative charges move along the y-axis in a magnetic field pointing up the z-axis, with force vectors perpendicular to both velocity and field direction.

A diagram showing a magnet being moved upward toward a conducting ring, with magnetic field lines passing through the ring. The induced current in the ring creates a magnetic field that opposes the magnet's approach, illustrating Faraday's and Lenz's laws of electromagnetism.

Diagram of an AC transformer showing a rectangular core with two coils of wire wrapped around opposite sides. The left coil is labeled N1 turns and E1, and the right coil is labeled N2 turns and E2.

Diagram showing a current labeled i charging a capacitor, with side-by-side panels. Each panel displays a blue arrow representing current flowing toward two capacitor plates-one with positive and one with negative charges. Large purple surfaces labeled P and S1 or S2 illustrate different surfaces intersecting the current path, representing Maxwell's displacement current in electromagnetism.

Illustration of Otto von Guericke standing beside his early electrostatic generator, holding a rod with a spherical end near a large mounted disk.

At a Glance

electromagnetism summary

electromagnetism

physics

Also known as: electromagnetic interaction

Written by

Frank Neville H. RobinsonAll

Fact-checked by

Britannica Editors

Last updated

Oct. 25, 2026 •History

electromagnetism, science of charge and of the forces and fields associated with charge. Electricity and magnetism are two aspects of electromagnetism. Electricity and magnetism were long thought to be separate forces. It was not until the 19th century that they were finally treated as interrelated phenomena. In 1905 Albert Einstein’s special theory of relativity established beyond a doubt that both are aspects of one common phenomenon. At a practical level, however, electric and magnetic forces...

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