# [SCI] Classical Electromagnetism

**Classical Electromagnetism** is the unified theory of electric and magnetic phenomena, culminating in Maxwell's equations (1865), which revealed that light is an electromagnetic wave.

## Overview

Michael Faraday discovered electromagnetic induction (1831) and introduced the concept of field lines, providing a physical picture of how electricity and magnetism are related. James Clerk Maxwell unified all known electric and magnetic phenomena into four differential equations, predicting that oscillating fields propagate as waves at the speed of light. Heinrich Hertz confirmed electromagnetic waves experimentally (1887), opening the path to radio and all wireless technology.

Maxwell's equations remain exact in the classical domain; they are Lorentz-invariant and were the empirical motivation for special relativity.

## Key Figures & Recognition

- **Michael Faraday** (1791–1867): Electromagnetic induction, field concept. No Nobel (predates prize).
- **James Clerk Maxwell** (1831–1879): *A Treatise on Electricity and Magnetism*, 1873. No Nobel (died young).
- **Heinrich Hertz** (1857–1894): Confirmed EM waves (1887). No Nobel (died young).

## Seminal Papers

- Maxwell, J.C. "A Dynamical Theory of the Electromagnetic Field." *Phil. Trans. R. Soc.* 155 (1865).
- Hertz, H. "Über Strahlen elektrischer Kraft." *Ann. Phys.* 272 (1888).

## What This Enables

- **[SCI] Electromagnetic Wave Theory** — Maxwell's equations directly predict transverse wave solutions propagating at the speed of light.
- **[TECH] Telegraph & Telephone** — Faraday's induction and Ohm's lawlaws make it possible to transmit encoded electrical signals down wirescurrent pulses along a wire.
- **[TECH] Electric Power Grid** — Electromagnetic induction (Faraday, 1831) is the operating principle of every generator and transformer.
- **[SCI] Electrochemistry** — Faraday's laws of electrolysis — charge drives chemical reactions — emerge directly from the EM framework.
- **[TECH] Electric Motors & Power Electronics** — Faraday's 1821 electromagnetic rotation experiment is the direct prototype of every electric motor.

# Parents

* [SCI] Newtonian Mechanics
* [SCI] Newtonian Mechanics
* [TECH] Precision Instruments